Open ahcorde opened 4 years ago
The elevation file (3601x3601) downloaded from https://earthexplorer.usgs.gov/ looks like:
after using the command
gdalwarp -te $WEST $SOUTH $EAST $NORTH $SOURCE_DEM $OUTPUT_DEM -ts 129 129
NOTE: You should visualize these images with qgis
otherwise you will see something like:
This is the metadata generated by gdalwarp
:
---- ExifTool ----
ExifTool Version Number : 10.80
---- System ----
File Name : sand_island_elevation.tif
Directory : media
File Size : 34 kB
File Modification Date/Time : 2020:04:15 15:16:35+02:00
File Access Date/Time : 2020:04:15 15:16:39+02:00
File Inode Change Date/Time : 2020:04:15 15:16:35+02:00
File Permissions : rw-r--r--
---- File ----
File Type : TIFF
File Type Extension : tif
MIME Type : image/tiff
Exif Byte Order : Little-endian (Intel, II)
---- IFD0 ----
Image Width : 129
Image Height : 129
Bits Per Sample : 16
Compression : Uncompressed
Photometric Interpretation : BlackIsZero
Strip Offsets : 1629 9627 17625 25623 33621
Samples Per Pixel : 1
Rows Per Strip : 31
Strip Byte Counts : 7998 7998 7998 7998 1290
Planar Configuration : Chunky
Sample Format : Signed
Pixel Scale : 8.99224806200556e-05 8.99224806201658e-05 0
Model Tie Point : 0 0 0 -157.89455503876 21.3179060387597 0
GDAL Metadata : <GDALMetadata>. <Item name="DTED_CompilationDate">0002</Item>. <Item name="DTED_DataEdition">02</Item>. <Item name="DTED_DigitizingSystem">SRTM </Item>. <Item name="DTED_HorizontalAccuracy">0009</Item>. <Item name="DTED_HorizontalDatum">WGS84</Item>. <Item name="DTED_MaintenanceDate">0000</Item>. <Item name="DTED_MaintenanceDescription">0000</Item>. <Item name="DTED_MatchMergeDate">0000</Item>. <Item name="DTED_MatchMergeVersion">A</Item>. <Item name="DTED_NimaDesignator">DTED2</Item>. <Item name="DTED_OriginLatitude">0210000N</Item>. <Item name="DTED_OriginLongitude">1580000W</Item>. <Item name="DTED_Producer">USCNIMA </Item>. <Item name="DTED_RelHorizontalAccuracy">NA </Item>. <Item name="DTED_RelVerticalAccuracy">0010</Item>. <Item name="DTED_SecurityCode_DSI">U</Item>. <Item name="DTED_SecurityCode_UHL">U </Item>. <Item name="DTED_UniqueRef_DSI">J19 065 </Item>. <Item name="DTED_UniqueRef_UHL">J19 065 </Item>. <Item name="DTED_VerticalAccuracy_ACC">0008</Item>. <Item name="DTED_VerticalAccuracy_UHL">0008</Item>. <Item name="DTED_VerticalDatum">E96</Item>. <Item name="UNITTYPE" sample="0" role="unittype">m</Item>.</GDALMetadata>.
GDAL No Data : -32767
---- GeoTiff ----
Geo Tiff Version : 1.1.0
GT Model Type : Geographic
GT Raster Type : Pixel Is Point
Geographic Type : WGS 84
Geog Citation : WGS 84
Geog Angular Units : Angular Degree
Geog Semi Major Axis : 6378137
Geog Inv Flattening : 298.257223563
---- Composite ----
Image Size : 129x129
Megapixels : 0.017
Bits Per Sample : 16 Sample Format : Signed
Is this format right for heighmaps?
@tfoote ote and @chapulina do you have some idea about what is going on here?
I have been checking
sand_island
andmcmillan_airfield
worlds. There is an issue with the resolution of the elevation files. For example, sand_island is 62x52 which is wrong according with the documentation. The right resolution is2^n + 1 x 2^n + 1
, for example 129 x 129, 513 x 513, etc.I have modified this line in the readme.md instrucctions:
to
But the elevation file is still wrong.