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Problem converting DEM meters to feet in QGIS raster calculator with manually rereferenced DEM

I generated manually rereferenced map (Indian Fork Rehab) and need to use the DEM to generate topo contours in feet. I'm using QGIS to generate the contours. The first step is to convert the DEM elevation data from meters to feet. Data range in meters is 1718.58 to 1761.01. When I do this conversion in Raster Calculator, it generates a new DEM with data range from -4.02449e-21 to 5777.59. Using Raster/Extraction/Contour causes QGIS to crash. 

If I do the same process using the DEM generated from the GPS georeferenced map output, this process works fine and I can get the one-foot topo contours with no problem.

Is there some limitation inherent in the GCP manual rereferencing process that makes it impossible to do the simple conversion of meters to feet? 

I've got a client that paid for the GCP surveys and is waiting for his topos! Can you help me out? Thanks

sageco

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There is no difference in the files as far as I know. The two versions below look the same as far as the basics go. 

Here is the GDAL info output from the original:

Driver: GTiff/GeoTIFF

Files: IndianForkRehab20191025-DEM.tif

Size is 12669, 10914

Coordinate System is:

GEOGCS["WGS 84",

    DATUM["WGS_1984",

        SPHEROID["WGS 84",6378137,298.257223563,

            AUTHORITY["EPSG","7030"]],

        AUTHORITY["EPSG","6326"]],

    PRIMEM["Greenwich",0],

    UNIT["degree",0.0174532925199433],

    AUTHORITY["EPSG","4326"]]

Origin = (-111.661862452798744,43.436085956945128)

Pixel Size = (0.000001655032299,-0.000001206174961)

Metadata:

  AREA_OR_POINT=Area

Image Structure Metadata:

  COMPRESSION=LZW

  INTERLEAVE=BAND

Corner Coordinates:

Upper Left  (-111.6618625,  43.4360860) (111d39'42.70"W, 43d26' 9.91"N)

Lower Left  (-111.6618625,  43.4229218) (111d39'42.70"W, 43d25'22.52"N)

Upper Right (-111.6408948,  43.4360860) (111d38'27.22"W, 43d26' 9.91"N)

Lower Right (-111.6408948,  43.4229218) (111d38'27.22"W, 43d25'22.52"N)

Center      (-111.6513787,  43.4295039) (111d39' 4.96"W, 43d25'46.21"N)

Band 1 Block=12669x1 Type=Float32, ColorInterp=Gray

  NoData Value=-32767

 

Here it is for the remapped version:

Driver: GTiff/GeoTIFF

Files: IndianForkRehab20191025-DEM (1).tif

Size is 12664, 10914

Coordinate System is:

GEOGCS["WGS 84",

    DATUM["WGS_1984",

        SPHEROID["WGS 84",6378137,298.257223563,

            AUTHORITY["EPSG","7030"]],

        AUTHORITY["EPSG","6326"]],

    PRIMEM["Greenwich",0],

    UNIT["degree",0.0174532925199433],

    AUTHORITY["EPSG","4326"]]

Origin = (-111.662974059173891,43.436028916878968)

Pixel Size = (0.000001853651661,-0.000001206405164)

Metadata:

  AREA_OR_POINT=Area

Image Structure Metadata:

  COMPRESSION=LZW

  INTERLEAVE=BAND

Corner Coordinates:

Upper Left  (-111.6629741,  43.4360289) (111d39'46.71"W, 43d26' 9.70"N)

Lower Left  (-111.6629741,  43.4228622) (111d39'46.71"W, 43d25'22.30"N)

Upper Right (-111.6394994,  43.4360289) (111d38'22.20"W, 43d26' 9.70"N)

Lower Right (-111.6394994,  43.4228622) (111d38'22.20"W, 43d25'22.30"N)

Center      (-111.6512367,  43.4294456) (111d39' 4.45"W, 43d25'46.00"N)

Band 1 Block=12664x1 Type=Float32, ColorInterp=Gray

  NoData Value=-32767

Zane 0 वोट
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I'm wondering if it is an issue of there being an additional NODATA value in the remapped version that is not showing up in the metadata. For example, is there perhaps a change between single precision floating point and double precision floating point in the remapping process that could lead to a different NODATA value that is not showing up in the metadata and therefore not being recognized by Raster Calculator as NaN?

sageco 0 वोट
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