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| TNM Historical Topographic Maps https://forum.transdem.de/viewtopic.php?f=8&t=662 |
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| Author: | fierogt87 [ 07 Apr 2023 23:22 ] |
| Post subject: | TNM Historical Topographic Maps |
hi  Don't the topographical maps downloaded from the US TNM server already have geolocation data? They come in GeoTiff or PDF formats. I can bring the geotiff files in as a raster map, but not as a georeferenced raster map. I don't know what to do with the PDF files. If i bring in a geotiff as a raster map, then georeference it in transDEM, I see it is now a .trf file. is there a way to bring these maps in with the existing geolocated data? Thanks Larry |
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| Author: | geophil [ 10 Apr 2023 10:45 ] |
| Post subject: | Re: TNM Historical Topographic Maps |
Not sure about the current start of their GeoTIFFs. TIFF and GeoTIFF are only standardized to a certain extend and have so many variables. GeoPDF should work, if you install the GDAL utilities, see the TransDEM main manual. |
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| Author: | fierogt87 [ 11 Apr 2023 03:39 ] |
| Post subject: | Re: TNM Historical Topographic Maps |
geophil wrote: GeoPDF should work, if you install the GDAL utilities, see the TransDEM main manual. Yeah, I have the GDAL installed, what I didn't know was how to get the GeoPDF into TransDEM. I piddled around a bit til I found it loads with 'Open Raster Map' instead of Open Georef. Raster Map'. Intuition drove me away from trying that. I got it sorted. Thank you! 
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| Author: | geophil [ 11 Apr 2023 06:44 ] |
| Post subject: | Re: TNM Historical Topographic Maps |
"Georeferenced" in the TransDEM philosophy means that it already has the TransDEM .trf file with the meta data. It also implicates that the raster map has been converted to UTM (or had been UTM all the way). Raster maps with the .trf file can be handled much more efficiently than the various kinds of raw maps, e.g. multiple maps can be opened simultaneously. Raw raster maps must be pre-processed individually. |
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