The US National Map

Earlier this month the US Geological Survey (USGS) released their latest version of The National Map Viewer.

US National Map View of Maumee, Ohio

The same view of Maumee, Ohio with the aerial image
background turned on

The US National Map is not a map per se.  You can't ring up the USGS and say "Send me a copy of the National Map."  It doesn't exist as a single product.  The US National Map is a collection of digital geographic and geospatial data that, when brought together, forms the foundational map of the United States.  Here's how the USGS describes it:

"As one of the cornerstones of the U.S. Geological Survey's (USGS) National Geospatial Program, The National Map is a collaborative effort among the USGS and other Federal, State, and local partners to improve and deliver topographic information for the Nation. It has many uses ranging from recreation to scientific analysis to emergency response. The National Map is easily accessible for display on the Web, as products and services, and as downloadable data. The geographic information available from The National Mapincludes orthoimagery (aerial photographs), elevation, geographic names, hydrography, boundaries, transportation, structures, and land cover. Other types of geographic information can be added within the viewer or brought in with The National Map data into a Geographic Information System to create specific types of maps or map views. The National Map is a significant contribution to the National Spatial Data Infrastructure (NSDI) and currently is being transformed to better serve the geospatial community by providing high quality, integrated geospatial data and improved products and services including new generation digital topographic maps."


OK, like I said, it's a collection of digital geographic and geospatial data that forms the foundational map of the US.  Geeze, I think government bureaucrats get paid by the word.

Here is the USGS's introduction to the National Map program and the National Map Viewer:



The National Map Viewer is the USGS's on-line portal to all the data that makes up the National Map.

The Viewer is pretty good (if you are at all interested, it is built on ESRI's ArcGIS Server technology) and offers some neat functionality.  It will provide location information in a number of formats, including US National Grid coordinates, it has a pretty robust reverse geocoding feature (click on a building on the map and the map returns the street address for that location) and it will provide spot elevations from the national elevation dataset.  You can do area and distance measurements, add text and simple graphics and even add data from external sources like a GoogleEarth KML file or a web mapping service.  You can also bring up indexes for the USGS's standard map products like the US Topo series of maps and link to them for download as GeoPDF files.  For advanced users the Viewer offers some pretty good search and query builder functionality, so you can find specific data that is embedded in the data layers.

There are some shortcomings, however.  The print function is essentially useless and is perhaps THE major drawback of this Viewer.  About all it does is grab a screen shot of your viewer and dumps it to a PDF file.  The USGS needs to wake up and realize that people still want quality paper maps and with today's technology it should be easy to print a fully detailed paper map with things like a grid, scale indicator, geographic extents, legend, etc.

The Viewer also exhibits a common issue found in web-based maps - map content naming conventions can be pretty obtuse and downright confusing.  While the Viewer does pretty good with the base data layer naming conventions, when you start using advanced features like the Query Builder you start to interact directly with the database field names.  For example, if I'm building a query to identify all the wetlands in my county I'm presented with a list of 'Columns' (which are the database field names).  Those column names are confusing and don't mean anything to most humans.  We get to pick from selections named 'ATTRIBUTE' or 'OBJECTID' or 'SHAPE_Area'.  There is an easy solution to this - the GIS professional building this map can establish what are called 'field alias' names - a human-friendly nickname for each of the information fields.  ATTRIBUTE can be displayed as 'Wetland Attribute', OBJECTID can be displayed as 'Wetland ID' and SHAPE_Area can be displayed as 'Wetland Area'.  This naming convention issue usually reflects the fact that GIS professionals with little cartography experience compiled the data for use in the Viewer.  (If I seem to be nit-picking here it is because I build maps for a living using this same technology.  I know these are issues that are easy to fix and should have been taken care of before the Viewer was opened up to the public.)

These shortcomings aside, the National Map Viewer is pretty darned good.  I'd say the USGS gets a good solid 'B' for this effort.  If they'd improve the damned printing issue I'd give them an 'A'.

Brian

Happy Birthday USGS

Missed it by a day, but Happy Birthday to the US Geological Survey!

The USGS was established on 3 March 1879, almost as an afterthought in a Federal budget submittal. It's stated mission was "classification of the public lands, and examination of the geological structure, mineral resources, and products of the national domain."

The first part of that mission, "classification of the public lands," was what drove a lot of the USGS's early efforts.  The US had acquired a lot of land as the result of the Louisiana Purchase and the Mexican War, but we didn't have a very good picture of just what it was we had gotten our hands on.  The USGS launched a standardized mapping effort that continues to this day, and will never really be completed.  Mapping the United States is like painting the Golden Gate Bridge, as soon as you finish at one end it's time to go back and start again at the other.

I'm hard pressed to name another federal agency that has done so much good work for both the nation as a whole and its citizens.

So here's the the US Geological Survey. Happy one hundred and thirty second birthday!

Measuring Things

US Coast & Geodetic Survey leveling party working in Atlanta, 1927

In the olden days, like before GPS, before you could make an accurate map real men had to go out and measure things.  This 'measuring' was called surveying, and it involved the extremely precise and accurate determination of the horizontal and/or vertical location of points on the ground known as survey control.  This survey control establishes the accurate framework upon which a map is built.  Horizontal measuring was called triangulation. Vertical measuring was called leveling.

The picture above comes from the US Coast & Geodetic Survey 1927 Seasons Report prepared by Captain E. O. Heaton (USC&GS).  It shows a topographic leveling party at work in Atlanta.  If anyone can figure out where in Atlanta these guys are working I'd love to know!  

A few things to note.  The fellow holding the umbrella is most likely a black local laborer hired to help the party haul equipment and provide general assistance.  The umbrella he's holding isn't to keep the surveyor from getting sunburned - it is to protect the instrument from direct sun and prevent glare when sighting through it.  To ensure accuracy survey parties often used umbrellas to shade their instruments and stabilize temperatures.  

The fellow squatting is a surveyor who is acting as the recorder.  He is writing down the readings being called out by the surveyor looking through the instrument.  The recorder's job was extremely important because he didn't just write down what the surveyor called out, he would do on-the-fly quality control checks on the values the surveyor gave him to ensure they were staying within the accuracy standards established for that particular survey.  If the recorder makes a single mistake, such as not catching an error in the surveyor's observations or by writing something down wrong (like inadvertently transposing a number or putting a decimal point in the wrong place) he could lose an entire day's work.  In my experience you wanted your  most meticulous guy and your best mathematician doing this job - perfectionists made good recorders.  The recorder is writing his notes down in a bound hardback book known as a survey field notebook.  That notebook would be turned in to the USC&GS at the end of the project and go on to become a part of the legal record of the survey.  I have no doubt that very notebook still exists in the archives of the USC&GS now held by the National Oceanic and Atmospheric Administration.  I'd love to take a peek at it!

(The job of recorder is one of those skills that has been replaced by computers.  Today's surveying instruments now automatically store the readings and calculate values internally.  The computer integrated into the survey level lets the surveyor know via a digital display if the readings are within the specifications set for the job.  It's called digital leveling.)

But what is the surveyor looking at?  Well, there are two people missing from this photo that make up the leveling party.  The surveyor is looking through the survey level at a stadia rod being held by another party member known as a rod man.  A stadia rod is a long pole marked off in feet and inches.  Behind the surveyor is another rod man with another stadia pole (the location of the stadia poles is determined by the survey party chief and is based mainly on topography and the ability to see both poles from where the survey level is set up).  The surveyor looks though the level and calls out the elevation mark he sees on the first stadia rod.  He then reverses direction and calls out the elevation he views on the second stadia rod.  The difference in numeric values he views on the two stadia poles is the difference in elevation between them:

Click on the image to open full size

Additionally, if this is a simple differential leveling job (and I think it is based on the type of level being used), there is another crew of chain men measuring the distance between the two stadia rods.  In 1927 this would have been done using steel survey tapes or chains.

Leveling is slow, tedious and physically demanding work.  There were no old farts out working on leveling parties except perhaps as party chiefs.  The rod men and the chain men were constantly moving, carrying the survey forward.  The instrument man and the recorder were responsible for moving and setting up the level in a new location, and the party chief was moving between all members of the survey party and scouting ahead for new setup locations.

Their work was absolutely critical, though.  The meticulous work of the surveyors of the US Coast & Geodetic Survey and the US Geological Survey created the accurate spatial framework that this countries maps and charts continue to be built upon.

But that's not the end of this story!  I got interested in this picture for a particular reason.  The vertical survey control for the airport I work at was established by this particular USC&GS survey project.  I would like to think that it was these three unnamed gentlemen who, sometime in 1927 or 28, ran their traverse down into College Park, GA and set the single elevation benchmark that became the origin point for all vertical survey work done at the airport until the advent of GPS-based survey in the late 1990s. 

Brian