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Edit 2 I figured out the problem. The download is a whole panel in the ballpark of 50 miles x 50 miles. The bounding box I requested was about 3x3 miles. My BB is a subset of the whole dataset that was sent to me.

I am downloading an elevation raster from the USGS national map. I am using the method where you view a map of the US and draw a box on it.

I am able to downoad the data and view in in ArcGIS Pro 1.3. But I am familiar with the topo of the area I am downloading, and it is clear that the area the National Map is sending me is not the same as the coordinates of my request bounding box.

How do I troubleshoot this? If I know my BB lat/long, is there a way to enter the coordinates numerically?

Edit 1

The link is: http://viewer.nationalmap.gov:80/basic/?basemap=b1&category=ned&q=&zoom=15&bbox=-81.90256119,35.87566326,-81.86385155,35.90215654&preview=&avail=&refpoly=

The product I am downloading is USGS NED 1 arc-second 2013 in GridFloat file format.

Here is the map on the screen of the National Map Viewer (in Internet Explorer): Table Rock in NC as seen from the National Map Viewer

It sends me a zip file with several files in it. The one with the data in it is floatn36w082.flt. I open this file from ArcGIS Pro (the problem seems to happen in other software as well. It's not a projection issue.) After loading the file in ArcGIS Pro, to help you see better what this terrain looks like (and for comparison, I process it with Shaded Relief, which renders this:

enter image description here

I hope all can see that the elevation data is not the same between these two images, regardless of the map projection. Table Rock (north of Morganton, NC) is a north-south running ridge line with the Linville River running north-south to its west. These features appear on the contour map I have uploaded.

Whereas the shaded relief image, downloaded from the National Map, has no river on the left and the ridge near the middle just looks way different. This is what makes me think the National Map is sending me elevation data for the wrong box.

The metadata xml files inlcudes

-<bounding>
 <westbc>-82.00166666667</westbc>
 <eastbc>-80.99833333334</eastbc>
 <northbc>36.00166666666</northbc>
 <southbc>34.99833333333</southbc>
 </bounding>

so it thinks it is at the right place. It is just that the topo does not look correct.

  • What is the projection of the data you're downloading and what is the projection you're viewing the data. I'm unfamiliar with Arc but checking the meta data could shed some light. – Knightshound Jul 26 '16 at 21:40
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The website always sends DEM files that are 1° wide and 1° high.

If you want a smaller area, you have to clip the downloaded data to a bounding box rectangle you need. Every GIS software is able to do that locally.

1

You have to be sure that the spatial reference of your lon/lat coordinates are the same of the elevation raster, the most common reference is WGS84.

Then, you can convert your coordinates into decimal values using the equation:

decimal value = degrees + minutes/60 + seconds/3600

check the webpage: Degrees, minutes, seconds to decimal degrees converter

  • Are you referring to the spatial refere5as it is in Arcgis? I am using the National Map Viewer website to download the data . The SR should be an implementation detail completely on the USGS server side. When I view the raster locally I know the SR is different. But I can still see there is no mountain where there should be a mountain. Can you clarify a little? – philologon Jul 26 '16 at 19:41
  • 1
    The spatial reference is standard, can you please send the link of the map you downloaded? – pateto777 Jul 26 '16 at 19:43
  • See the edits I just made in the original Question section. – philologon Jul 26 '16 at 22:35

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