Whence The Meridian?

It seems that most folks' awareness of history reaches back only 20 or 30 years.  Few today can conceive of a world without laptop computers, cable TV, cell phones and Dancing With The Stars.  Oh how dark and disordered life must have been before the internet!  How did man survive?

Old farts like me realize that history is a cumulative progression of events, and the things we take for granted today had an origin in the murky mists of time long past.

So it is with the concept of longitude and the meridian.  Today we take for granted that the zero line of longitude, the international meridian, runs through Greenwich, England.  It seems just so natural.  Most people today don't realize that getting the meridian at Greenwich accepted as the world-wide standard was a long, drawn out process that spanned over a hundred years and involved most of the major world powers.  What we take for granted today is actually the result of some pretty intense diplomatic and scientific battles.

Man has realized since the time of the ancient Greeks that the Earth is round(ish) and that one of the best ways to refer to one's position on this big ball is to use angular measurements - degrees, minutes and seconds.

On land this convention wasn't really important - the common man was content relating his location as distance and direction traveled from known points.  There was always a track, trail or road that led to where he wanted to go.  The history of the march of civilization is the history of road building.  It's coded into our DNA.

But as soon as man started sailing out of sight of land things changed.  There are no roads in the middle of the Atlantic.  All sailors had to fall back on was positioning by latitude and longitude.  With the explosion of maritime trade in the 18th and 19th centuries most of the big navigation problems were quickly worked out.  By the late 1700s we had reliable navigation instruments (sextants and chronometers), most of the important places of the world had been charted and sea captains could reliably and safely make their way to the other side of the world and back carrying cargoes that made the ship's owners immensely wealthy.

But there was one last international navigation issue that was was still hanging out there in the late 1800s that needed to be addressed.  The issue of a common meridian.

Latitude and longitude are calculated from an accepted reference line, or zero line.  For latitude the solution was simple.  The equator is the natural zero line of reference.  When calculating latitude you are measuring your location north or south of the equator - the zero line of latitude.  Simply measure the angular distance from your location to the North Star - Polaris - and you have your latitude in degrees, minutes and seconds.  Mariners around the world have been doing this since before recorded history.  (If you are south of the equator it's a little trickier since there is no star that hovers directly over the south pole.  However, there are nearby stars such as those that make up the Southern Cross that permit similar measurements.)

Longitude however has always been the problem child of navigation.  Part of the problem is that there is no natural zero line of longitude - the earth does not have a natural vertical equator.  The other problem is that there are no fixed or unmoving celestial bodies - stars or planets - that could offer an easy reference for longitude measurements like Polaris does for latitude measurements.  All the useful celestial bodies are in constant motion overhead.  What was needed was first a fixed reference line - a meridian - and then in reference to that line the minute-by-minute locations of all useful stars and planets as they marched across the sky.  The designation of the meridian also drove the publication of accurate nautical charts for use by merchantmen and navies.  This was a monumental task that only governments could support.

The realization that establishing a meridian and charting the night skies was a national necessity coincided with the scientific revolution of the 1700s.  Nations were willing - even eager - to put their money and their best minds to the task; it became an issue of national pride among the major seafaring nations.  Most also saw it as a national security issue.  These efforts were some of the earliest examples of directed research - scientific investigation not for the sake of enlightenment but to meet a specific economic or military goal.

As a result everybody who fancied themselves a bigshot on the global stage established their own meridian and published navigational charts and celestial almanacs referenced to their meridians.  Most also required their navies and merchant fleets to use their meridian.  Countries such as England (Greenwich), Spain (Madrid), France (Paris), United States (Washington D.C. and Philadelphia), Portugal (Lisbon), Norway (Oslow), Russia (St. Petersburg) and Japan (Kyoto) all developed their own meridians.  Even non-seafaring nations like Switzerland and Romania tried to get in on the act.

By the mid 1800s the worldwide nautical charting community had become a seafaring Tower of Babble; not everybody spoke the same positional language.  At the same time the development of reliable steam power was driving an explosion of commercial shipping activity.  As merchant marine activities became more globalized ship captains, owners and insurance companies began demanding standardized navigational charts and nautical almanacs.  A ship captain sailing from Boston needed to know that when he got to Lisbon and needed a new chart he could walk into a chandler and purchase a chart that uses to the same meridian he was trained to use and was comfortable with.  Seafaring nations realized that a single universally recognized meridian was a good thing.  But whose meridian would be the winner?

In 1884 the President of the United States, Chester A. Arthur, got representatives from all the key nations together in a big room at the State Department in Washington D.C. and told them to figure it out.  By this time the US really didn't have a dog in the fight; although we were willing to accept Greenwich, England as our standard Prime Meridian we were open to switching and were not going to push a US-based solution.  My guess is that most of the attendees saw the US as something of a neutral party in this argument, which is why they agreed to show up and work things out.

The 'International Conference For the Purpose of Fixing a Prime Meridian and a Universal Day' was convened on October 1st 1884 and ran for the full month.  The proceedings can be found on the Project Gutenberg website.  The proceedings are an interesting read from a historical, scientific and political perspective.  The delegates from France did a lot of talking, extolling the glories of the Empire and the primacy of the observatory in Paris.  In the end however Greenwich in England won out, in large part, I suspect, because at the time over 72% of the world's shipping used nautical charts based on the Greenwich meridian.  The Greenwich solution had the weight of numbers behind it and came without a lot of Gallic preening and posturing.

And so we have the Final Act:

Note who decided to take a pass on the final vote.  Sore losers I guess.

The conference addressed and adopted a number of other issues including the designation of a 'universal day'.  This is why we have Greenwich Mean Time, or GMT (also referred to as UTC) and the standard solar day starts, and ends, at Greenwich.

After the conference the US Congress moved quickly to adopt Greenwich as the standard prime meridian for all US-based mapping and charting.  The US Navy and the Royal Navy began working jointly on the development and maintenance of nautical almanacs for celestial navigation and the sharing of nautical charts.  This is a collaboration that continues to today.

So there you have it.  Something a seemingly mundane as the starting point for all longitudinal measurements around the world actually has a history that impacts us today.

Brian

A False Sense of Confidence

For Christmas my lovely wife gave me a new GPS receiver.  At work I'm surrounded by some of the most expensive and precise GPS surveying technology available today - devices that can reliably locate you to within a few centimeters of your true position.  What I didn't have was a consumer grade GPS device that I could take out hiking or fishing.  It seems Roberta read my Dear Santa letter and got me a DeLorme PN-60 receiver.

Many of you are probably asking, "why not just use your iPhone?"  Good question.  While I love my iPhone experience has taught me that it makes a lousy GPS receiver.  It may locate you good enough to allow accurate vehicle navigation while cruising up the interstate and it may provide good enough locations to allow you to update your Facebook status, but as a dedicated GPS tool it just doesn't cut it.  To be fair, the iPhone does excel is as an integrated device for wayfinding.  Apple's integration of hardware and mapping software makes the iPhone a wonderful and reliable urban navigation tool.  However, most of this functionality is dependent on a wi-fi or 3G signal, making the device unreliable for use in the backwoods.

What I wanted was a dedicated GPS that is rugged, water resistant, accurate and allows me to upload maps and aerial photos.  The PN-60 seems to fit that bill just fine.

Of course the first thing I had to do is take it out and play with it!  A few days after Christmas I loaded the dogs into the old Volvo wagon and we headed out to one of my favorite parks with walking trails.  This park, Lake Horton, is located in Fayette County and has a number of walking trails that skirt the lake.  Once we got there I leashed up the dogs and set the PN-60 to generate a track file (basically recording my location every 10 feet).  The trail we walked is a 1.8 mile long trace that moves through a mix of topography - some open ground, some heavy canopy cover, some areas where the canopy obscures just half the sky.  It is a good test environment for a GPS receiver.

Let's pause for a minute to review just how GPS works.  The GPS receiver establishes a position by a triangulation process that uses signals from the GPS satellites in orbit around the Earth.  A GPS receiver needs good signals from at least three GPS satellites to calculate a useable position in 2 dimensions (horizontal).  Note that the key word here is useable, not accurate.  To get a useable 3 dimensional position (throwing elevation into the mix) the receiver needs good signals from at least four satellites.  The accuracy of the position your receiver calculates is highly dependent on a number of factors such as satellite geometry (where they are in the sky overhead), how healthy the satellites are (yes, there are 'healthy' and 'unhealthy' GPS satellites), the amount of overhead interference (things like heavy tree cover, tall buildings, etc.) and the overall sensitivity and accuracy of the receiver itself.  All of these factors have a vote in how accurate or inaccurate you GPS location will be.  The only fixed variable in this equation is the capability of your GPS receiver; all other factors can vary from minute-to-minute and location to location.

Just how accurate can a GPS receiver be?  The US Air Force, which operates the GPS system, states that civilian users can expect the GPS system to provide position fixes to within 100 meters 95% of the time.  That's pretty darned conservative and assumes a very basic early generation receiver that is not applying any modern GPS correction signals from systems like the WAAS satellites (Wide Area Augmentation System).  

The civilian GPS industry tosses around the number 15, as in 15 meters.  A modern consumer grade GPS receiver operating under open sky and in the static mode (not moving) should provide a fix to within 15 meters (49 feet).  If the receiver is WAAS-capable (and most are) then that potential accuracy should drop to about 3 meters (10 feet). This is about the best a modern consumer grade GPS unit can be expected to do.

This big improvement in accuracy has come through improved receiver hardware and software.  GPS receiver manufacturers have gotten pretty good at this business over the past 20 years and they've developed some nifty tricks to greatly improve overall accuracy and satellite signal acquisition speed and lock.  A modern GPS receiver, even a relatively inexpensive recreational unit like the PN-60, is a marvel of modern hardware and software design.

Now back to our regularly scheduled blog post...

So the dogs and I walked the 1.8 mile trail and then rushed home to upload the GPS track file to the DeLorme Topo North America desktop software to see what was recorded.

Zoomed out it looked sort of OK; at least I was on the right part of the world.

DeLorme Topo North America 9.0 (click on image to enlarge)

But when I zoomed in to specific sections of the track I noticed some concerning issues with how the recorded GPS track was lining up with the portions of the trail visible in the image.

25 ft. offset between the walking trail and the GPS track
(click on image to enlarge)

Note the high tension lines running north-south across the image.  This is a potential source of interference.

Next:

38 ft. offset between the walking trail and the GPS track
(click on image to enlarge)

Note the heavy canopy coverage immediately south of the trail.  Heavy tree canopy can either block or interfere with GPS signal quality.

Next:

An average 10.2 ft. offset on a section of trail with light overhead canopy
(click on image to enlarge)

In an area with fairly open sky (and well away from powerlines) the average offset drops to just over 10 feet, perfectly acceptable accuracy for this receiver operating in the moving mode.

Next:

Offsets ranging from 14.5 ft. to almost 25 ft. in an area of completely open sky
(click on image to enlarge)

What's going on here?  This is an area of completely open sky - no trees or other obstructions.  Accuracy should be much better than what we are seeing here.  Well, if you look closely you can just make out the trace of the high tension power lines cutting across the lower right hand corner of the image.  My suspicion is that the powerlines are interfering with the GPS signals.

And last:

Two sample areas in close proximity - one showing a 60.7 ft. offset and
one showing almost negligible offset
(click on image to enlarge)

This example clearly illustrates the impact of heavy tree canopy cover.  The upper measurement, taken in an area of dense canopy cover, shows an almost 61 foot offset between the walking path and the GPS track.  However, just 55 feet to the south, under fairly open sky (and with no power line interference) the offset is so small as to be negligible.

So what can we learn from this simple example?  Let's review:

1. The manufacturer's stated GPS accuracies are for their products operating under the most ideal conditions - open sky, with good satellite geometry and no electromagnetic interference.  Your real world results can, and will, vary widely.

2. Overhead or adjacent obstructions like trees can have a dramatic effect on GPS accuracy.

3. Unseen influences like nearby powerlines can have significant impact on GPS accuracy.

4. In areas of little obstruction or interference consumer grade GPS receivers can achieve their claimed accuracy of +/- 3 meters (10 feet) in the moving (tracking) mode.

So what can you do to improve your GPS receiver's accuracy?  Here's a few tricks:

1. Make sure WAAS is turned on.  On most receivers sold in the US it is turned on by default, but you still need to check.

2. Make sure position averaging is turned on.  While this won't help when moving, when stopped to record a position (waypoint) if you let the receiver average your position for a few seconds before storing it your accuracy can improve dramatically.  When collecting waypoints I'll try to let the receiver average between 5 and 10 seconds before storing the point.

3. Hold or carry the receiver so that the antenna is fully and properly exposed to the sky.  Don't expect a GPS receiver buried deep inside a backpack or tucked inside a shirt pocket to return a good position.  Your receiver has to 'see' the GPS signals and anything you can do to improve it's view of the sky will result in more accurate positions.

Understand your potential sources of error!  Remember how the system works - radio signals from space.  If you understand what can interfere with those signals and you remain observant of your environment you can often work around these sources of error.

So many people I talk to about GPS have a false sense of confidence about GPS accuracy.  The vast majority think their receiver is far more accurate than it really is.  While the GPS satellite system and our modern receivers are true marvels of modern technology the system still has plenty of real world limitations.

Brian

Note: I do have to add that the measurements I show in the images above also have a lot of built-in but uncontrollable error.  The DigitalGlobe images I'm measuring against have an advertised resolution of 30 centimeters (roughly 1 foot).  Assuming these images were processed without a tight orthorectification their inherent positional error can range from 2 - 5 feet (my estimation).  In this blog post I'm not trying to establish absolute accuracies or inaccuracies for a given receiver.  I just want to give the reader as sense of what impact physical and electromagnetic interference can have on GPS accuracy.

To The Corps!

I spent most of my military career serving either as a Topographic Officer (21C) or a Terrain Analysis Warrant Officer (215D) in the Army Corps of Engineers.  It was clear throughout most of my career that the Engineer branch really didn't know what to do with us.  US military doctrine said that the Corps of Engineers 'owned' the topographic and terrain analysis (military geography) discipline, but owning and effectively managing are two different things.  The field was so small and specialized that the Engineers tried to manage it by exception, as though we were all infected by some pox and couldn't be treated as real Engineers.  

However, this was not always the case.  For several decades in the first half of the 19th century two military engineer organizations ran parallel to each other in the US Army.  One organization was filled with officers with mostly limited engineering backgrounds.  This group was detailed to handle general engineering support to field units, tackling simple engineering tasks like improvements to local fortifications, managing the construction of tracks and trails in support of military movement and doing local reconnaissance and field sketching in support of military operations.  These were the regular Engineer forces assigned to the field Army.  The other group was filled with the cream of the graduating classes from West Point and some of the top graduates of the few engineering schools operating in the US the time.  This group handled most of the civil works improvement projects along the coastlines and interior waterways and mapped the new western territories and opened them for exploration and settlement.  This last group truly was the civil engineering force for the new nation and was known as the Corps of Topographical Engineers.

Uniform button design for officers assigned
to the Corps of Topographical Engineers.  From the
1832 Uniform Regulations:
"Buttons--gilt, seven eights of an inch diameter, slightly convex: device,
 the shield of the United States, occupying one half of the diameter:
 letters T.E. In Old English characters, occupying the other half;
small buttons, one half inch diameter: device the same."   

From roughly 1812 to 1863 the Corps of Topographical Engineers operated as an independent organization, sometimes as a separate branch within the War Department, sometimes as a wholly autonomous section within the Army Engineers.  The 'Corps' was little more than a roster of officers detailed to the Topographical Engineer branch.  There were no enlisted personnel assigned and Topographical Engineers were usually dependent on local Army commanders to provide the needed manpower for projects.  What the Corps of Topographical Engineers did have was some of the best civil engineering minds in the nation.  At a time when trained engineering expertise was hard to come by - civil engineering as a defined discipline wouldn't emerge until well after the Civil War - the Army and Congress often turned to the Corps of Topographical Engineers to handle most of the early public works planning and management.   Topographical Engineers explored and mapped the Great Lakes region, managed canal construction and waterways improvements and even surveyed and planned lighthouse locations.  In the 1850s, when the federal government needed to have the lands acquired from Mexico and the newly incorporated State of Texas explored and mapped, they sent in the Topographical Engineers.  When Congress needed to know if there were suitable routes through the Rocky Mountains for the planned transcontinental railroad they sent the Topographical Engineers to have a look.  Once the Oregon Territory dispute was settled with England the Topographical Engineers moved in to map the rugged interiors of what is today Oregon, Washington and Northern California.

Regulation on how officers assigned to the
Corps of Topographical Engineers are to be detailed,
or appointed to duties.  Excerpted from the
'Army and Navy Chronicle', January 2, 1840

In 1863 the Army folded the Corps of Topographical Engineers into the regular Corps of Engineers and a proud organization that provided immeasurable service to the nation disappeared.  I guess it was inevitable since there was a desperate need for trained Engineer officers to support the Federal armies during the Civil War, and there was growing overlap in the roles of the two organizations.  

The Corps of Engineers love affair with it's mapping and surveying mission waxed and waned over the next 150 years.  Engineer officers still found themselves assigned to important topographic missions as America settled it's western territories, rushed to map its newly acquired territories after the Spanish-American War, threw armies across the seas in World Wars One and Two and stared down the Soviets during the Cold War.  I believe the peak of the Corps of Engineers interest in and dedication to its topographic mission came with the establishment of the Army Map Service in WWII.  The Engineers realized they had to get damned serious damned fast about this mapping thing and developed the doctrine, equipment, techniques and technology necessary to produce maps and related products to support a world-wide war effort.  This effort continued well into the Cold War, and it was the Army Map Service (and later the Army Topographic Command) that gave us groundbreaking developments such as the Universal Transverse Mercator grid system, the Military Grid Reference System and early research work on an earth-centered geoid that ultimately became WGS 84.

As the Cold War wound down the Corps of Engineers interest in its mapping mission wound down too.  As more and more map production was pushed to the national level (to the Defense Mapping Agency, which became the National Imagery and Mapping Agency, which became the National Geospatial-Intelligence Agency) and mapping systems moved from paper to digital and became embedded in  battlefield command and control systems, the Engineers seemed on a headlong march to shed their traditional topographic role.  Inevitable?  Perhaps.  Wise?  I don't think so.  Topographic knowledge is the foundation of military expertise.  Great generals like Napoleon, Lee and Grant, and Patton all talked about the necessity of being able to visualize the battlefield, the ability to identify 'good ground'.  Someone will always have to paint the battlefield picture for the generals, and that's the job of the Topographic Engineer.

Although the Corps of Topographical Engineers has faded into history they are not forgotten.  There is a small but active group that keeps the history of the early Topographical Engineers alive through research and reenactments.  They are the U.S Corps of Topographical Engineers.  Their website is a great resource for anyone interested American history and the story of how America grew in the early 19th century.

U.S. Corps of Topographical Engineers website.

So here's to the Corps!  To a group of dedicated Topographical Engineers that explored, mapped and helped build this great land.  Ladies and gentlemen raise your glasses.

To the Corps!

Brian

Brain Droppings

Naaah, I haven't been ignoring this blog.  I've just been busy.  It's just one of those times when one's personal and professional life get a little crowded and you get distracted.

So anyway, what have I been working on that is related to maps, mapping, topography, GIS, et. al.?

Actually, quite a bit, although the activity is more of a low murmur rather than a series of 'ta-da!' moments.  Let's begin...

ArcGIS Online.  Aaah, the software I hate to love.  I can't discuss too much detail right now because we are involved in the beta test program (and that imposes some confidentiality rules on us), but it is starting to look like the new ESRI ArcGIS Online for Organizations program is shaping up to be something of a game changer for enterprise web mapping, particularly for small and medium organizations that can't afford or don't need heavy iron IT backbones to get their jobs done.  The ArcGIS Online program is part of ESRI's cloud GIS strategy and I for one like the direction it's going.  This program will allow many - perhaps a majority - of organizations that develop and deploy GIS web maps to leave their in-house IT departments behind.  It is not a complete solution, but it takes the field a lot further down the path of IT independence than we've ever seen.  Anything that helps destroy the perception that GIS is just another IT discipline is great.

By the way, you do have your ArcGIS Online accounts set up, don't you?  And you are using the free ArcGIS Online web mapping tools right?

Mobile Mapping.  This is loosely tied to the ArcGIS Online initiative.  We are testing some new mobile solutions that utilize the ArcGIS applications developed for Apple's iOS (iPad and iPhone) and Google's Android OS (smartphones and tablets).  While you will still need ArcGIS Server (but hey, that can reside in the cloud now, too), these new mobile apps make it easier to create and deploy lightweight apps that include a basic level of interactive field data creation and editing.  I'm sure we'll see more of this at the next ESRI User's Conference.  It's slick!

To The Cloud!  Lately I've been absolutely fascinated by the concept of cloud computing and I've been poking around in that realm just to see what's possible, what's not possible and what will be possible in the months or years to come.  Folks, this is the future of computing.  As Steve Jobs would say, it's 'the next big thing'.  Surprising then that Apple is still stumbling at getting their cloud computing programs up and running.  The idea of an OS-agnostic computing environment that maintains all your information in a secure data store on the internet (i.e., the cloud) and can be accessed from any computer through a simple web browser is compelling.  Apple, Google and Microsoft are in a mad race to stake out their territory in the cloud, but it's clear that Google has taken an early and substantial lead.  That's not surprising, given that cloud computing has been at the core of Google's business strategy been for years.  That's OK because Google's competitors are in a hurry to catch up, and the inevitable struggle for our attention (and dollars) will make this an exciting wrestling match.  I'm gonna' go grab a tub of popcorn and a Coke and watch the show from the cozy comfort of my iPad.

Oh, and keep your eye on the new kid on the block - Amazon.

Well, that's it for now.  What's up next?  Probably something to do with CAD & GIS integration methinks.

Brian

Spy Satellites Declassified

A KH-9 Hexagon Imagery Satellite.  The thing's as big
as a Greyhound bus!

On 17 September 2011 the US declassified the KH series of satellites and their mission information.

Guess now I can tell my wife what I was doing for most of those 23 years I was in the Army.

What's not discussed in the story, and I won't go into too much detail until I know for sure it's OK to discuss it in full, is the contribution these satellites made to the DoD's world-wide mapping program.  Suffice to say, without these birds we would not have been able to accurately map the vast territories of the Soviet Union, Eastern Europe, China and all the other hostile places we thought we might have to go fight in.

More to follow...  Maybe.

Brian

The Software I Hate To Love

In the Geospatial Engineering world there is one Big Dog software developer and a pack of miniature chihuahuas snapping at its heels.  The Big Dog is ESRI, developers of the ArcGIS suite of software products.

ESRI dominates the GIS (geospatial information systems) software field in the same way Microsoft dominates the computer operating system field - there are competitors but nobody even comes close to the market share that ESRI developed and has held for decades.

But unlike Microsoft, ESRI didn't get to where it is by being predatory and imposing crushing licensing agreements on its clients.  ESRI got it's market share the old fashioned way - by simply being the best product in the market for the target consumer group.  ArcGIS is the software product that moved the traditional discipline of topography out of the paper map and overlay era and into the computer-based, analysis driven discipline of Geospatial Engineering.

ESRI was started by Jack Dangermond, someone I refer to as a "Birkenstock wearin', Volvo drivin', granola crunchin' hippie."  In the late 1960s and early 70s, building on pioneer work that had been done on early GIS concepts and development in Canada (where the discipline of GIS got its start), Dangermond created a land cover analysis program called ArcInfo and released it as a commercial product in the early 1980s.

Early versions of ArcInfo were hindered by limited computer processing, storage and graphics capability.  Geospatial analysis is very much a visual discipline - you're making maps, after all.  Early desktop hardware simply didn't have the capability and capacity to bring the full visual mapping experience to the user.  Up through the mid 1990s only expensive Unix workstations could handle that level of processing.  This all changed around 1995 when desktop computing power started increasing exponentially with each new processor design while at the same time hardware prices dropped like a brick.  Almost overnight inexpensive desktop computers appeared that could easily handle the processing and graphics demands a software package like ArcInfo placed on them.  I was working as a GIS program manager for the US Army when this hardware revolution hit the field and watched as in less than two years inexpensive desktop PCs caught up with and then quickly surpassed the processing power of the Unix-based Sun, Silicon Graphics and HP  systems we had been relying on.  What also helped was Microsoft's release of WindowsNT at about the same time.  Finally we had a serious network-ready enterprise operating system running on high capacity hardware that didn't make our budget guys weep every time we said we needed to do an upgrade.

ArcInfo is the flagship product of the ESRI line and is extremely powerful software.  But in the 1980s ESRI realized that not everyone needed the processing power of ArcInfo (nor could they afford the nausea-inducing cost of an ArcInfo software license).  ESRI introduced a lightweight version of ArcInfo that included most of the visualization capability of the high end package but left out the heavyweight analysis and data development functionality.  They named it ArcView.  It was priced right - something small organizations and even individuals serious about GIS could afford (if I remember correctly the GSA schedule price for a single ArcView license ran around $600 in 2000).  The vast majority of today's GIS professionals cut their teeth on ArcView.

But ESRI's real contribution to the GIS profession is the development of data types that both support complex spatial analysis and can be shared across different software platforms.  It is Dangermond's vision that GIS-based mapping and analysis solutions should not be a stovepipe, but a shared resource.  This drove ESRI to develop the concept of the geodatabase.  A geodatabase is a collection of data in a standard relational database management system (RDBMS) like Oracle or SQL Server, but the data has very unique spatial values (location in x, y and z coordinates) assigned to it.  This means that GIS software can leverage the spatial values to relate the data in a location context and other RDBMS-based software systems can easily share their information with the geodatabase.   The geodatabase only needs to store GIS-unique features and can pull and do analysis against associated data in another database.

ESRI also developed a version of the geodatabase that does not require a high powered relational database management system as it's foundation.  About a decade ago ESRI introduced the concept of a file-based geodatabase designed for use by small organizations or groups.  The file geodatabase is a simple to create yet powerful and extremely flexible data format that brings most of the power of the relational database and complex data analysis to the desktop machine and the individual user.

But what does the future hold?  ESRI realized long ago that the Internet was the map content delivery vehicle of the future.  Paper maps were headed to obsolescence and what Jack Dangermond describes as the 'rich web map' would quickly become the geospatial data visualization and analysis tool of the future.  He's right, but only very recently has web technology started to catch up with his vision.

For the better part of a decade it was possible to hire professional web developers to create some very nice web mapping applications built on ESRIs early web technology called ArcIMS.  The problem was that those applications were difficult to develop, difficult to maintain, and required a lot of heavy weight back-end web and database server technology.  Only large enterprises and governments could support the hardware, software, development and maintenance costs.  ESRI's web solutions were very much limited by the immature web development technologies available at the time.  It is ESRI's vision that even the average geospatial professional working for a small business or local government should be able to develop, launch and maintain high quality web maps that bring value to the organization they support.  ESRI started laying the groundwork for this vision back with their ArcGIS 9 series of software releases and the development of things like ArcGIS Server and the concept of Map Services.  Two years ago they released ArcGIS 10 that brought a lot of maturity to the concept of integrated and streamlined web mapping using the Microsoft Silverlight and Adobe Flex web development environments, and the launch of ArcGIS Online with its peek into the future concept of 'cloud services' for hosting GIS data, services and web maps.

At it's recent worldwide user's conference ESRI announced the pending release of ArcGIS 10.1 with better integrated and streamlined web development tools.  But ESRI also announced two new developments that are generating a lot of interest.  The first is the announcement that ESRI has partnered with Amazon.com to host robust, enterprise-level cloud services for GIS web mapping, data hosting and application development.  The idea is that an enterprise purchases an ArcGIS Server software license, passes that license over to Amazon and Amazon stands up and maintains the necessary database and web development environment for the enterprise.  This is a huge development because it can free the GIS group supporting the enterprise from the often onerous and restrictive shackles placed on it by their local IT department.

The other announcement was the pending release of the ArcGIS Online Organizational Account program.  The Organizational Account program appears to be targeted as smaller enterprises and groups that don't have the money or need to purchase full-up cloud services like those offered by Amazon.  Under the Organizational Account concept an organization will be able to purchase data and web hosting services from ESRI on a subscription basis.  It is still a 'cloud' model, but on a smaller, more tailorable scale that should allow small organizations to enjoy most of the capabilities of a full-up ArcGIS Server implementation.

The last good thing I need to discuss is another little-known program released this year - the concept of ArcGIS for home or personal use.  ESRI's software licensing fees have escalated to the point that the geospatial professional simply can't afford a copy to use to keep his or her skills sharp.  I noted above that the GSA price for an ArcView license used to run about $600 - a bearable cost if you were serious about GIS.  However, the cost for an ArcView license now hovers around $1,600, far too much for even the serious home user.  This year ESRI announced the ArcGIS for Home Use program.  Anyone can purchase a 1-year license of ArcView for $100, a very reasonable price.  Not only does this $100 include on-line software training and support, but you also get a very extensive suite of add-on modules like 3D Analyst, Spatial Analyst and Geostatistical Analyst.  The total value of the software you get for your $100 subscription comes to over $10,000.  One hell of a deal.  Of course there are restrictions attached to this deal.  The intent of the home use program is just that - you can only use it at home.  You can also only use it for personal development/training purposes or non-profit use.  Still, like I said, it's one hell of a deal.

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Now, it's not all rainbows and unicorns when it comes to ArcGIS and ESRI's position in the GIS world.  All this GIS goodness is of little use unless it's leveraged in an environment with clearly defined professional standards.  Nor can you allow a professional discipline to be defined by a software application or be inexorably joined to a piece of software.  This is where ESRI's has failed the geospatial community, and they have failed in ways they can't even visualize from where they sit.

Here's the reality: geospatial engineering is the discipline, the term geospatial information systems - GIS - merely describes the tools geospatial professionals use to do their job.  Where ESRI has failed is in using its industry position and influence to help clearly delineate the difference between the two.  As a result, far too many engineering professionals view geospatial professionals as little more than button pushing software monkeys, one step up from data entry clerks.

Part of the culture Jack Dangermond has fostered and progressed through ESRI is the idea that GIS is for everyone and nobody owns it.  What he is effectively saying is that GIS is the discipline; the tools and the software drive the field, not the other way around.

While community ownership is a noble goal, ESRI's dominance of the field gives lie to that very philosophy.  Effectively, ESRI 'owns' GIS; it is by far the world's largest GIS software developer.  It has either developed or successfully implemented most of the recognized spatial analysis processes in use today.  It's data management features have driven the development of most of the spatial data standards in use today.  The vast majority of geospatial professionals worldwide learned their trade using ArcGIS.

What is lacking, however, is a clear and recognized definition of just what a geospatial professional is.  Dangermond is correct when he claims it's not his role to define what a geospatial professional should be - that is the job of the geospatial field and industry as a whole.  But Dangermond has been the biggest catalyst in the geospatial world for the last 30 years.  He and the resources he commands through ESRI have been in the best position to cajole and coerce the private sector, academia and the government to establish the roles, practices and responsibilities that define Geospatial Engineering as a formal discipline.  He should have been the single biggest champion of the concept of Geospatial Engineering as a professional discipline.  Instead he's been pretty much silent on the whole issue.

It is only in the last few years that the US Department of Labor developed a formal competency model for GIS (GIS, not Geospatial Engineering), and the GIS Professional Certification program is just starting to get its feet on the ground (after a disastrous grandfathering period that allowed perhaps hundreds of clearly unqualified individuals to get a GISP certificate and do damage to the reputation of the geospatial profession that may take years to overcome).  Great, but all this should have happened 20 years ago.

What this means is that Geospatial Engineering is not respected as a professional discipline.  I can tell you from long personal experience that geospatial professionals are looked down upon by other disciplines such as civil engineering and surveying, in large part because there are no testable and enforced standards that define us as a 'profession'.  Guess what - they are right!

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Many readers are probably asking themselves "Huh?  What's he getting at here?"  I guess I'd ask the same question myself if I didn't understand the background issues.

I've been a topographer and geospatial engineer for over 30 years.  A few months back I laid out my initial arguments in a post titled In Praise of the Old Topographer.  In that post I made the argument that Geospatial Engineering is just a logical continuation of the older and much respected profession of Topographer.  I also outlined my argument that geospatial information systems, including ArcGIS, are merely the tools that the Geospatial Engineer uses to do his or her job.

With this post my goal was to identify one of the main culprits that is keeping Geospatial Engineering from fully maturing into a recognized profession, a profession with it's own standards, roles and responsibilities.

ArcGIS is that culprit.  On the one hand we have extraordinarily capable software that is almost single handedly responsible for bringing the discipline into the computer age and is poised to bring it fully into the age of  world wide web.  On the other hand, ArcGIS and it's parent company ESRI are almost single handedly responsible for holding the discipline back and keeping it from taking it's rightful place as a profession on par with other engineering disciplines.

For these reasons ArcGIS is the software I hate to love.

Ohio Is Such a Mess

"On the road above the Bell Company's dock, Pennsylvania Route 68 invisibly changes to Ohio Route 38, and trees half hide some signs by the roadside.  The place could hardly be more anonymous.  Even someone familiar with the historical significance of this particular spot, who has traveled several thousand miles to find it, and whose eyes are flickering wildly from the narrow blacktop to the grassy verge between the road and river, can drive a couple of hundred yards past it before hitting the brakes.


The language of the signs is equally undemonstrative.  A stone marker carries a plaque headed "The Point of Beginning" that reads "1112 feet south of this spot was the point of beginning for surveying the public lands of the United States.  There on September 30th, 1785, Thomas Hutchins, first Geographer of the United States, began the Geographer's Line of the Seven Ranges."


There is nothing to suggest that it was here that the United States began to take physical shape, nothing to indicate that from here a grid was laid out across the land that would stretch west to the Pacific Ocean, and north to Canada, and south to the Mexican border, and would cover more than three million square miles, and would create a structure of land ownership unique in history..."


                                                                         - Andro Linklater, "Measuring America" (2002)


In his wonderful book 'Measuring America', author Andro Linklater explains in detail just how it is that the concept of property ownership, and in particular the ownership of land, is the cornerstone of the American republic.  America was founded on the concept of property rights, and there is no greater realization of that concept than the idea that the common man can buy, hold and own land and that he, his family and his descendants will prosper and profit from the ownership and improvement of land.  The land does not belong to a government or a sovereign, but to the people.  It was a radical concept in 1776 and it is still very much a unique concept in the world today.

At the end of the Revolutionary War the weak federal government was cash poor but increasingly land rich.  Under the Articles of Confederation the federal government had no authority to raise revenue through taxation - that power was still retained by the individual states.  But the states were defaulting on their obligations to provide funding for the federal government.  The federal Army had not been paid for months and was on the brink of mutiny.  We had no navy to speak of.  Revolutionary War veterans were holding IOUs from the Continental Congress that were about to come due and our overseas creditors were demanding payment.  In desperation the federal government turned to the only asset it had available - land.

The Treaty of Paris that ended the Revolutionary War gave the new American nation control of a large tract of land west of the Ohio River in what is today southeastern Ohio.  This was really the only tangible asset the federal government owned that was not already claimed by one of the 13 states.  Almost in desperation, the Congress of the Confederation  hit on the idea of land sales as a way to support the struggling federal government.  The idea was simple - divide up the land and sell it for a dollar an acre.  Cash only, no credit!

But how to divide it?  This new nation needed a land measurement and inventory system that was logical, easy to implement and resulted in land parcels that could be easily and quickly sold.  The resulting system, codified in the Land Ordinance of 1785, gave us what we know today as the township and range land survey system.  Conceptually is was simple - divide the land into six miles square sections (townships), then subdivide each township into one mile square sections, then further into quarter sections.  The initial unit of sale was a quarter section of 640 acres.

But where to start?  The Congress of the Confederation set up a committee to study the issue and appointed Thomas Hutchins, a noted military engineer and surveyor, as Geographer of the United States.  It was decided to start the land survey at the point where Pennsylvania's northwestern boundary intersects the Ohio River.  This point became the Point of Beginning for all public land surveys in the United States.

So, on a blustery day in late September, 1785, Thomas Hutchins and his survey party walked down to the banks of the Ohio River, drove a stake in the ground, set their survey instruments up and began to lay out what became known as the Seven Ranges region of Ohio.

From this Point of Beginning Thomas Hutchins set in place the land survey system that would ultimately encompass 75% of the land mass of the United States, clearly establish and define private land ownership and set the stage for the explosive westward expansion of the US in the 19th century.  On September 30th, 1785 Thomas Hutchins literally drove the stake that established the geographic fabric upon which the United States was built.

View Larger Map

Ohio was to be the proving grounds for the township and range survey system.  Like a lot of first tries at anything problems cropped up, adjustments were made and shortcuts were taken.  Part of the problem stemmed from the fact that much of the land in what we today call Ohio was subject to prior claim.  Large areas of  northern Ohio were ceded to Native Americans under various treaties.  Connecticut claimed a large region stretching from present day Sandusky, Ohio east to the Pennsylvania border.  Virginia claimed a large tract in the south to use to compensate her veterans.  Other bits and pieces here and there were set aside.  Ohio was a patchwork quilt of land claims, set-asides, treaty lands and private holdings.

Ohio Land Claims - 1800's

But very quickly another series of problems popped up.  Congress was pressured by speculators to sell large chunks of land.  Congress saw this as a way to generate quick cash - sell land at a slight discount for immediate payment and let the speculators carry the cost of the land surveys.  The land speculators saw it as a road to riches - if they could sell fast.  But before any land could be sold it had to be surveyed and the surveys registered.  That meant the surveys needed to be done fast.  Accuracy be damned!

In the 18th century anyone with rudimentary math skills and who could afford a surveyor's compass and chain could call themselves a surveyor, and many did.  Since surveyors at the time were paid by the mile the faster they worked the more they got paid.  This meant the surveys were sloppy and niceties like calculating the local differences between true north and magnetic north were either not done as often as required or simply not done at all.

As a result, a lot of Ohio's township and range section lines take off at odd angles and don't quite form square parcels.  Eventually the errors accumulated and corrections had to be made.  Often it was the simple expedient of offsetting a north-south range line at the start of the next township line.  Since roads in Ohio tended to follow the township and range section boundaries this led to the quirky (and often dangerous) tendency of country roads ending at a T-intersections for no apparent reason, then picking up again about 100 feet east or west of the end point.  These little jogs are a modern reflection of the corrections the surveyors were forced to build into their work over 200 years ago.

Other times the errors were so extreme that there was really no way to correct them and the government was just forced to incorporate the errors into the public record as-is:

The intersection of surveys for the Symmes Purchase, Virginia Military Reserve
and standard Public Land Survey areas.  There are about three different
interpretations of true north indicated by these township and range layouts!

So there you have it.  Ohio is a darned mess.  But a fascinating mess that leaves us the physical traces of the birth of the survey system that made westward expansion possible.

Brian