Need help with using The National Map website

[bigben]

A very rough walkthrough.... QGIS example using NAIP.

* Get QGIS (http://qgis.org/) and start the desktop program
* Layers > Add layer > Add WMS/WMTS layer
* Copy this URL into the URL field: http://raster.nationalmap.gov/ArcGIS/services/Orthoimagery/USGS_EROS_Ortho_NAIP/ImageServer/WMSServer
[attach=1]
* Connect to the service, select the layer, add it and close the dialogue window
[attach=2]
* Zoom to the area you want (or use the coordinate/scale boxes at the bottom of the screen)
* Right click on the layer name and select "Save As"
[attach=3]
  * Enter a directory to save the image(s)
  * Click on Map Extent button to save just the area displayed
  * Enter the horizontal and vertical resolution (decimal less than 1)  Use the same number for both so that you get square pixels. The total image dimensions will appear in the "columns" below.  This gives you control over the image resolution so you don't have to download more than you need.

Hit the OK button and it will get 2000x2000 pixel geotiff tiles and put them in the specified directory. 
[attach=4]

If you want the raw resolution data, Enter the resolution as 1/display scale. eg. if the scale is 1:10,000 use a resolution of 0.00001.

No messy searching for tiles, multiple download links, registration/logins. Get what you want at exactly the resolution you want.

[Ashley]

@bigben
That looks awesome, thanks for outlining the process :-)

[chrisshort]

Thanks! A walk through is just what the Dr. ordered. I do have That program to try.

Thanks Also to Oshyan for explaining how to use the NAIP in Terragen directly. This needs to be documented somewhere as it isn't obvious that this method exists....

Thanks to all!

[bobbystahr]

No, HGT should be height as far as I know, not orthoimagery. But the original discussion seemed entirely focused on aerial/satellite imagery, the height data seemed to be coming in fine. So I was answering the original question. *Your* data download is probably height and should be loaded on the Terrain tab with Add Terrain -> Heightfield Load (use Load Multiple DEMs if you have more than one, though I think you're using free version and this option may not be available).

- Oshyan

That's the route I took Oshyan, but they all loaded at 0,0,0 so I missed a step obviously...will read more now I know they load fine. Thanks.

[chrisshort]

For color images, you want to go to the Shaders tab, click Add Layer, and choose Load Multiple Geog Image Map Shaders. Then you should be able to load all your JP2s. I would not trust Photoshop to represent them properly, they may indeed be grayscale, but perhaps not...

- Oshyan

OK, Attempted to load the NAIP files. Here is the current situation. What was downloaded based on my selection was two DEM files and 6 NAIP files (1 through 6).  I load both DEMS and all 6 NAIP files. They all have the geo referencing on.  I then change the planet apex to one of the NW corners to have the dem oriented in my view (Is is correct?).

I don't see the mapping yet so I check the coordinates of the images and they don't match the proper location. If I plug in each corner info of one of the dems (Because that is the only info I have)  map 1 shows up over that particular DEM (which is expected) but I'm sure the 6 images needed to be sized to cover the two dems and I don't know where to get the info of each corner of each image. The email of the download only gave me "Current Extent/(-105.125, 38.825), (-105.016, 38.92)" for each of the six images while the dem's seem to cover -106 through -104 and 39 through 38.

Is it possible the NAIP files don't have the Geo referencing attached and I need to manually get the coordinates for each segment?  Bummer if that is true...

[Oshyan]

It sounds like either the data does not have georeferencing information embedded in it, or TG is not reading it right. You would need to confirm the existence and accuracy of any georef data in it by using another app like Global Mapper. Perhaps BigBen can have a look?

- Oshyan

[bigben]

JPEG, JP2 doesn't support embedded coordinates. This info is usually included in a metadata file with the image, although some sites just provide the image. In those cases you'd need to record the corner coordinates and projection when acquiring the data. If you have this info you have to manually georeference the image in TG.

Geotiff is by far the easiest format to use for TG. QGIS is a bit... OK, a LOT... quirky if you're not used to all of the techy GIS stuff, but the workflow I described above is relatively easy and gives you geotiff.  I tried adding similar WMS services for elevation that appear in GlobalMapper, but it looks like GlobalMapper has a lot of hidden smarts to make accessing the data really easy. I'll make a tutorial if I can figure out some of my data workflows with QGIS in a reasonable simple way.

[chrisshort]

JPEG, JP2 doesn't support embedded coordinates. This info is usually included in a metadata file with the image, although some sites just provide the image. In those cases you'd need to record the corner coordinates and projection when acquiring the data. If you have this info you have to manually georeference the image in TG.

Geotiff is by far the easiest format to use for TG. QGIS is a bit... OK, a LOT... quirky if you're not used to all of the techy GIS stuff, but the workflow I described above is relatively easy and gives you geotiff.  I tried adding similar WMS services for elevation that appear in GlobalMapper, but it looks like GlobalMapper has a lot of hidden smarts to make accessing the data really easy. I'll make a tutorial if I can figure out some of my data workflows with QGIS in a reasonable simple way.

Thanks for the input! In the case of the NAIP files, Since it was broken up into 6 parts and only give one overall coordinates, how would I know how to do the coordinates for the 6?

[bigben]

If it's lat/long projection (safest bet to start with anyway), there'll be a direct correlation of pixels to coordinates. If the images are not all the same size, just calculate the size in degrees of 1 pixel (lat/long difference divided by total image height/width) and then go from there.