The best way to get elevation / displacement map for 3ds Max ?

spooks2k1spooks2k1 Global Mapper UserPosts: 16
Hi, I'm trying to create a black and white displacement map for some landscape in 3ds max.

I'm currently using DEM format and opening it up in Photoshop with the Geographic Imager plugin, this is the best method I've found to convert the DEM to a B&W gradient image.

I'm using Aster GDEM v2, the area is roughly 12 x 9 km.

I Export DEM, vertical units in meters with 15m sample spacing in the X & Y, I tried 1m but the file size was huge 4gb+.

This creates a DEM image of 180mb, and when I convert it to PNG for the displacement the resolution is 20503 x 13406.

I've reduced it down, but it seems a little blurry, should I expect more detail from the Aster GDEM ?

I tried geotiff, but my results were blocky and pixelated, DEM was to only way I could get a decent image.

I appreciate this may not be the way to go about things, so If someone could outline the steps to get Aster GDEM at the highest resolution it would be greatly appreciated, I'm trying to get the most optimal workflow down.

tia

http://i.imgur.com/ywVA4eW.jpg


Best Answer

  • MykleMykle Global Mapper User Posts: 382
    Answer ✓
    The resolution of your elevation data (from any source) can be found in the metadata that is available for any raster layer that is loaded in Global Mapper. 

    SRTM data are defined as having a resolution of 3-arc-seconds, or 90m at the equator.
    The latest SRTM data have a resolution of 1-arc-second, or 30m at the equator. 
    ASTER GDEM data also have a resolution of 1-arc-second, or 30m at the equator. 
    USGS DEM have a nominal resolution of 1/3-arc-second, or 10m. 
    USGS DEM in some areas are available at 1/9-arc-second, or ~3m. 
    LIDAR data sets MAY provide higher resolution.   It's up to you to see what you really have. 

    Map tile zoom level 19 implies a resolution of 0.3m. 
    http://wiki.openstreetmap.org/wiki/Zoom_levels

    For data exports, when you specify any resolution that is higher than your data, some sort of interpolation is required, smoothed or not.  Specifying a higher resolution than supported by your data will not result in more detail, however smooth the pixels may appear. 

    The Blue Marble folks should be able to say what smoothing is done for displayed data and for exported
    data.  The smoothing, if any, may differ by export format. 

Answers

  • MykleMykle Global Mapper User Posts: 382Trusted User
    You can load ASTER elevation data directly into Global Mapper using the on-line links.  Then, look at the metadata for your data to discover the resolution.  It will probably be in the range of 45m per pixel (roughly half the classic 90m SRTM data).  If you can find 30m SRTM data for your area, it may be better.  You do need to look at your data and determine if it will be satisfactory for your purpose.  I frequently find ASTER data to be more noisy, for example. 

    Then you can export your data in your choice of format, and your file is probably going to be georeferenced.  Photoshop will remove any georeferencing data, however if you don't change the dimensions and resolution then you may be able to use an accompanying projection or world file to provide at least some of the georeference details. 
  • After you loaded the elevation data for the area you can draw a rectangle to crop it and in the meantime you can measure the sizes of said rectangle so you know the actual size of what you export. You can also see the min and max elevation so you will know the z scale to use in 3d. Now show a gradient shader in the main view. At this point you can simply export a png cropped to the rectangle you created and you can use it as displacement map.

    I used this way for Blender landscape generation so it should work well in 3dmax as well.

    Best regards 
    Michele 
  • spooks2k1spooks2k1 Global Mapper User Posts: 16
    Thanks guys, I'm already using the ASTER GDEM v2 Worldwide Elevation Data from the Online Data Sources.

    I know how to work GM to the point of exporting, what I'm trying to find out is my export the best quality.

    The only "issue" I'm having is with the resulting black and white image, "issue" meaning is this the best I can expect from Aster Gdem and Global Mapper ?

    Photoshop doesn't remove the georeferencing data if you use the Geographic Imager plugin, but I don't need the referencing I just want the best quality black and white image for the displacement.

    Is the image I posted above the best I can expect ? Should it be that blurry ? what are the optimal settings when exporting dem ?

    Are there any benefits to using GeoTiff over Dem for best resolution/detail ?

    My main sticking point is with the export, the Sample Spacing Scale. I'm using UTM Projection my height is set to meters.

    When Exporting dem I tried the Sample Spacing Scale at 5 meters in the X and Y which is the image I posted above, then I tried it at 1 meter, the resulting file was over 4gb, and the image looked the same only much bigger, it looked like I'd resized the 5 meter version to a higher resolution resulting in low detail and blurriness.






  • MykleMykle Global Mapper User Posts: 382Trusted User
    What does your ASTER metadata report for resolution?  Any exports with higher resolution "should" not be any different, regardless of how high you go (other than filesize).  It is hard for us to evaluate "blurriness" without a scale (it's all relative, right?). 

    If you want to compare other data sources (SRTM, DEM, whatever), you should be able to assess "detail".  I will frequently load data from multiple sources, if only to get a better feel of their relative resolutions. 

    You can also export data at a variety of resolutions above and below the value reported in metadata.  Then you can load each of these exported files and compare them by turning layers on and off. 

    Global Mapper in v17 and before had an option to Show/Hide layers in the Overlay Control Center so you could "blink" compare sets of layers, but it has not (yet) been included in v18 and the programmers have not (yet) committed to keeping this option.  So anyone else that misses it should help with the chorus and speak up (!), since my solo won't be enough to get it done. 

    Thanks for the description of your workflow.  That helps.  (gotta look at the Geographic Imager plugin)
  • My normal process is to export GeoTiff. Convert to RGB in Photoshop, and save as .EXR (greatly reduces filesize over TIFF) for displacement in 3DS Max. Larger areas may just require a tile export?

    Hope that helps.
  • spooks2k1spooks2k1 Global Mapper User Posts: 16
    Cheers for the replies guys, the problem I'm having is with resolution and which settings to use to get the best resolution for both imagery and elevation.

    When I use Geotiff for elevation grid format, I get very pixelated results which is why I switch to dem.

    For world imagery, what is the process for exporting the imagery at optimum resolution ? How do I configure things so I know I'm exporting at full zoom level?

    In SAS Planet I can download tiles at z19, (zoom level) as far as I know this is the best resolution of the image.

    What is the equivalent in GM ?

  • spooks2k1spooks2k1 Global Mapper User Posts: 16
    edited November 2016
    Ah kerching! the pennies finally dropped, thanks Mykle that helps explain things.

    GM defaults to the metadata resolution when I export, so it seems I was doing it right all along. I just over complicated things with the elevation data, I assumed the resulting image would be bigger, but at 38m a pixel it's obviously already exporting at full resolution, and there's no point in a higher one as all it does is increase the file size with no detail gain.

    Thanks for your patience in explaining, I'm visual hands on learner, so the written form usually takes a few attempts  :smiley:
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