Hi John

The VRT you have generated lacks the CRS information, but looking at the
corner numbers, it looks like it could be EPSG:2391 (NZGD2000 / New Zealand
Transverse Mercator 2000).  Of course this is a guess, I'm not sure on this.

As Axel has pointed out, the next step is to check if each source tiff file
is georeferenced. This can be done at the command line:
gdalinfo /home/sdc4/GeoMaps/Featherston_BP33_GeoTifv1-08.tif
and so on.

If all source files are georeferenced, the VRT is expected to be created
without problems. (take in mind that all source files must have the same
CRS).

Anyway, you can manually declare a CRS for the resulting VRT by adding the
-a_srs option to the gdalbuildvrt command. (Normally it is not necessary to
use the gdalwarp command). example:
gdalbuildvrt -a_srs EPSG:2391 Map.vrt georefmap1.tif georefmap2.tif
georefmap3.tif

The above is for the command line, but you can also do it in QMS with the
"Build VRT" tool.  In the VRT builder dialogue, to manually declare the CRS
you should check the "Advanced options", and fill in the -a_srs box by
typing EPSG:2391 (or whatever you need).
*** Be careful... when you click on "advanced options" you run the risk of
becoming an advanced user ;-) Or at least you are on it !
Try it and let us know

HTH

mitxel


El mié, 21 abr 2021 a las 11:10, APM (<[email protected]>) escribió:

> I'm not a professional in geotiff/gdal , but it seems that your maps are
> not georeferenced.
>
> "Coordinate System is `' " should contain a valid value.
>
>
> You can check with gdalinfo, if your input tifs are ok.
>
> Maybe they have no or different systems.
>
>
> Your can find out, which CRS your source maps should contain and add a
> system with gdalwarp.
>
>
> See https://gdal.org/programs/gdalwarp.html
>
>
> Sample: gdalwarp -t_srs EPSG:4326 input.tif output.tif
>
> But as mentioned before I'm not very fimilar with it.
>
>
>
> Good luck!
>
> KR
>
> Axel
>
>
>
>
> Am 21.04.21 um 10:54 schrieb John Groombridge:
>
> On 21/04/21 8:25 pm, APM wrote:
>
> maybe you can try to get more information with gdalinfo Map.vrt
>
>
> Whow, that was quick. Thank you Axel
>
> gdalinfo WELLINGTONarea.vrt:
>
> Driver: VRT/Virtual Raster
> Files: WELLINGTONarea.vrt
>        /home/sdc4/GeoMaps/Featherston_BP33_GeoTifv1-08.tif
>        /home/sdc4/GeoMaps/Kapiti_BN32pt_GeoTifv1-06.tif
>        /home/sdc4/GeoMaps/LakeWairarapa_BQ33_GeoTifv1-05.tif
>        /home/sdc4/GeoMaps/LowerHutt_BQ32_GeoTifv1-08.tif
>        /home/sdc4/GeoMaps/Paraparaumu_BP32_GeoTifv1-09.tif
>        /home/sdc4/GeoMaps/Wellington_BQ31_GeoTifv2-04.tif
> Size is 17010, 22678
> Coordinate System is `'
> Origin = (1731997.883333333302289,5502002.116666666232049)
> Pixel Size = (4.233333333333330,-4.233333333333330)
> Corner Coordinates:
> Upper Left  ( 1731997.883, 5502002.117)
> Lower Left  ( 1731997.883, 5405998.583)
> Upper Right ( 1804006.883, 5502002.117)
> Lower Right ( 1804006.883, 5405998.583)
> Center      ( 1768002.383, 5454000.350)
> Band 1 Block=128x128 Type=Byte, ColorInterp=Red
>   Min=0.000 Max=255.000
>   Minimum=0.000, Maximum=255.000, Mean=138.955, StdDev=100.317
>   Metadata:
>     STATISTICS_APPROXIMATE=YES
>     STATISTICS_MAXIMUM=255
>     STATISTICS_MEAN=138.95493788032
>     STATISTICS_MINIMUM=0
>     STATISTICS_STDDEV=100.31731040258
>     STATISTICS_VALID_PERCENT=100
> Band 2 Block=128x128 Type=Byte, ColorInterp=Green
>   Min=0.000 Max=255.000
>   Minimum=0.000, Maximum=255.000, Mean=145.367, StdDev=102.848
>   Metadata:
>     STATISTICS_APPROXIMATE=YES
>     STATISTICS_MAXIMUM=255
>     STATISTICS_MEAN=145.36712569726
>     STATISTICS_MINIMUM=0
>     STATISTICS_STDDEV=102.84783150571
>     STATISTICS_VALID_PERCENT=100
> Band 3 Block=128x128 Type=Byte, ColorInterp=Blue
>   Min=0.000 Max=255.000
>   Minimum=0.000, Maximum=255.000, Mean=131.932, StdDev=107.121
>   Metadata:
>     STATISTICS_APPROXIMATE=YES
>     STATISTICS_MAXIMUM=255
>     STATISTICS_MEAN=131.93187872401
>     STATISTICS_MINIMUM=0
>     STATISTICS_STDDEV=107.12126613018
>     STATISTICS_VALID_PERCENT=100
> ____________________________________
>
> How does that look?
> --
>
>
> Kia ora
>
> *JohnG*
> _______________________________________________
> *using LINUX :: an operating system immune to Windose viruses*
>
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