Satellite Imagery DEM Files

DEM files are great for creating a basis in reality for environments. There is a little big of a work flow to use them but it is totally worth it. First, go to website to download the dem data. I use National Maps. They revamped the website so it took me a little bit to get used to the new gui. At first glance there is a ton of different ways to get data. Easiest way is click “Maps” in center image.

dem_1_nat_map

This takes you to the download area. You get a map for all of the US (National map is only USA, there are other sites to use for rest of the world). Pick an area you’d like to explore. I’ve used Google Earth to do my location scouting and then come to National Maps after. Click the bottom icon in the red box I’ve indicated. This will put a “pin” on the map, or you can use the “box” icon and drag anywhere you’d like. Larger areas will utilize multiple maps. The “trash can” deletes your selection.

dem_2_nat_map

Click “Customs Views” on top bar. Here you select the type of data you want. For DEMs we’ll need “Elevation”. You can do multiple selection just one at a time or do view all. Imagery will be satellite color photos to go with your height map info.dem_3_nat_map_elevation

Select the type of “Elevation” data you want. The file are usually in arc-second format. Easy way to remember is 1 arc second is 30 meters per pixel, so 1/3 arc sec is 1 meter per pixel. Plenty big for what you need. The File format is “Arcgrid” because I use Global Mapper to convert the DEM data so Photoshop can read the files. Click “Find Products”.

dem_4_nat_map_arcgrid_

You can add as  many files as you need. Either use the shopping cart method and do 1 massive download session, or singularly. I like to see my region before downloading. Click “Footprint” to get a box on the map, “Thumbnail” to see a grey image of what you are downloading on the map, and “Zoom to Info/Metadata” to zoom into the area.

dem_5_nat_map_arcgrid_icons

It’s much easier to see what you are going to get and where it is on the map.

dem_6_nat_map_arcgrid_footprint_zoom

Download away if you are happy with it.

dem_7_nat_map_download

On to Global Mapper. Click “Open Your Own Data Files”

dem_8_global_mapper

Go to your National maps downloaded file. Go inside folders and find largest file in there. That’s generally the DEM data. Click “use all file formats” if the file folder looks empty.

dem_9_global_mapper_import

Global Mapper processes the info and here you go.

dem_10_global_mapper_dem_data

Now just export out your image as needed so Photoshop can read the file.

File – Export – Export Elevation Grid Format.

dem_11_global_mapper_export

Use “GeoTiff”.

dem_12_global_mapper_geoTiff

You’ll get Export Options. Choose “Elevation 32 bit” on first tab.

dem_13_global_mapper_32bit_tif

On the 3rd tab, you can choose “Draw a Box” and a pop up will appear to draw an area you’d like to export. This is good if your area is quite large. Click “ok” when done.

dem_14_global_mapper_draw_box

Now open your file in Photoshop. Hmmmmm….just white document.

dem_15_psd_32bit_tiff

You’ll need to convert to a 16 bit file. Image – Modify – 16 bit. You do this after in order to get highest fidelity file first then down sample. Keep Custom on and drag Edge Glow parameters to closest to zero.

dem_16_edit_modify_16bit

You can do whatever you want at this point. You’ve effectively saved a Displacement map of your satellite imagery. You can use Maya, World Machine, Vue, or whatever. I’m going to World Machine, then to Vue.

Open a “File Input” in World Machine, and path to your Photoshop converted file.

dem_17_wm_image_file_input

Run whatever operations on it. I did just a simple “Erosion” on it.

dem_18_wm_erosion

Add a file export and geo export. This covers my basis for whatever package I go next.

dem_19_wm_ouptu

Open vue, pick an atmosphere, and add a terrain node.

dem_20_vue

Double click the terrain. Delete the terrain history by clicking the top left icon.

dem_21_vue_terrain_editor

It’s now just a plane. Click the “Import image” icon.

dem_22_vue_fileimport

Click import again to get your file.

dem_23_vue_get_file

Click the Folder icon. Navigate to your folder.

dem_24_vue_get_file

Boom, you now have your DEM data in Vue. Click ok. Make sure your resolution on top middle is high enough. I’m at 2048×2048.

dem_25_dem_as_terrain

Orbit around, find a good angle. Render.

vue_dem_render

This needs work in Vue but you get the idea. You can utilize any terrain in 3d! You can also follow these steps again for the satellite color information for your maps as well.

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