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Extract TTM / Surface

  • 1.  Extract TTM / Surface

    Posted 06-18-2023 16:22

    I've been forwarded the below tif - is it possible to extract / create a surface model from this data ?

    SH25A_TAPARAHI_NZTM_NZVD16_31_May_2023_SH25A_Merged_230531_dsm.tif



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    John Mill
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  • 2.  RE: Extract TTM / Surface

    Posted 06-18-2023 19:31

    Sorry it is not possible to extract surface data from a TIFF file in TBC. Do they have the data in any other formats?



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    James McWha
    Asia Pacific Regional Support Manager, Geospatial
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  • 3.  RE: Extract TTM / Surface

    Posted 06-19-2023 12:35

    As I understand it, a TIF (or TIFF) file can be any of these:

    • A regular image, with no geographic location information
    • A GeoTIFF, which has the location, or "world file" embedded, but no elevation information
    • A GeoTIFF, which has the location, or "world file" embedded, but the colors of the image represent the elevation of each pixel.

    The one you posted appears likely to be a regular image and not a GeoTIFF since the red area is all the same color. You may want to ask for a GeoTIFF or some other format as James suggested.

    If you go to the Import screen in TBC, it will examine each file and determine whether it's a regular TIF or a GeoTIFF.

    We regularly import TIF's from USGS, which are GeoTIFF's that represent the surface as obtained by Lidar. They come in quite nicely as a surface.

    I'm still learning how all of this works, so anyone feel free to chime in and clarify. I won't be offended.



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    Bob Epstein
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  • 4.  RE: Extract TTM / Surface

    Posted 06-20-2023 08:10

    Bob I think you are on the right track with your explanation. TBC does not handle raster surface models well.  If you opened that surface file with another program like Global Mapper or QGIS you would get a different image than the red and blue you see in TBC.  Is it possible to Post the tiff here so I can have a better look at it and see what information is available?

    SL



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    Scott Lehr
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