I have an elevation DEM in the form of a GeoTIFF file downloaded from USGS for a southern California area near Chatsworth CA. I noticed so far the the default co-ordinate system seems to be EPSG:4326 WGS84 with the elevations in meters.
I tried many ways to convert the CRS to NAD83 California Zone 5 along with the elevations and so far only the X and Y axis and not the elevation data are converted. I also tried to convert the elevation data over to feet with gdalwarp however I was not yet successful at doing so. When I checked my elevations they were still in meters.
I tried to convert the elevations over to feet by applying a scale factor:
"your_raster_layer" * 3.28084
So far I couldn’t get the raster calculator to accept the input. There was a dialog box that came up stating that something about my input was incorrect. Could I get some assistance please, how to use the raster calculator with this type of DEM from USGS in GeoTIFF format to apply the conversion factors to the elevations after I converted to NAD83?
P.S.
I seem to remember using QGIS a while ago and finding California Zone 5 in my basket of CRS’s however this time around I am only finding NAD83 UTM 11. Is there a way to get back or download CRS for California Zone 5 of NAD83?
Grab it from https://www.usgs.gov/the-national-map-data-delivery/gis-data-download . It’s in UTM there
On Sun, Aug 25, 2024 at 6:34 PM Cristoforo Montanari via Qgis-us-user <qgis-us-user@lists.osgeo.org> wrote:
I have an elevation DEM in the form of a GeoTIFF file downloaded from USGS for a southern California area near Chatsworth CA. I noticed so far the the default co-ordinate system seems to be EPSG:4326 WGS84 with the elevations in meters.
I tried many ways to convert the CRS to NAD83 California Zone 5 along with the elevations and so far only the X and Y axis and not the elevation data are converted. I also tried to convert the elevation data over to feet with gdalwarp however I was not yet successful at doing so. When I checked my elevations they were still in meters.
I tried to convert the elevations over to feet by applying a scale factor:
"your_raster_layer" * 3.28084
So far I couldn’t get the raster calculator to accept the input. There was a dialog box that came up stating that something about my input was incorrect. Could I get some assistance please, how to use the raster calculator with this type of DEM from USGS in GeoTIFF format to apply the conversion factors to the elevations after I converted to NAD83?
P.S.
I seem to remember using QGIS a while ago and finding California Zone 5 in my basket of CRS’s however this time around I am only finding NAD83 UTM 11. Is there a way to get back or download CRS for California Zone 5 of NAD83?
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I don’t have the time for the real question but I can provide the Scale Factor.
3.28083333333…or
3937/1200
Beware the international foot. It will be standard soon…
0.3048m = 1 ft
Then the scale factor will be 10000/3048
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J. Thaddeus Eldredge, PLS, CFM
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I always use the raster calculator.
I found a write up here: https://tinkerprojects.xyz/nerd-stuff/convert-a-dem-file-from-meters-to-feet-in-qgis/
If you are having trouble with the QGIS raster calculator you can try the GDAL one in the processing toolbox. https://docs.qgis.org/testing/en/docs/user_manual/processing_algs/gdal/rastermiscellaneous.html#gdalrastercalculator
···
J. Thaddeus Eldredge, PLS, CFM
East-SouthEast, LLC
1038 Main Street
Chatham, MA 02633
508-945-3965
www.ESE-LLC.com
PRIVACY NOTICE - This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. You are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.
Sebastian "Bas* " Gutwein
*rhymes with Josh
Regenerative Design Group
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(631) 241-1018
Look close, think big, make change.
I don’t know which version of QGIS you’re using - I have 3.34.9 up and running.
In my case I have a DEM (named dem) and my raster calculator expression is:
“dem@1” * 3.28081
I also have the output layer specified although I could create a temporary layer.
Randy
···
On 8/25/24 18:34, Cristoforo Montanari via Qgis-us-user wrote:
I have an elevation DEM in the form of a GeoTIFF file downloaded from USGS for a southern California area near Chatsworth CA. I noticed so far the the default co-ordinate system seems to be EPSG:4326 WGS84 with the elevations in meters.
I tried many ways to convert the CRS to NAD83 California Zone 5 along with the elevations and so far only the X and Y axis and not the elevation data are converted. I also tried to convert the elevation data over to feet with gdalwarp however I was not yet successful at doing so. When I checked my elevations they were still in meters.
I tried to convert the elevations over to feet by applying a scale factor:
"your_raster_layer" * 3.28084
So far I couldn’t get the raster calculator to accept the input. There was a dialog box that came up stating that something about my input was incorrect. Could I get some assistance please, how to use the raster calculator with this type of DEM from USGS in GeoTIFF format to apply the conversion factors to the elevations after I converted to NAD83?
P.S.
I seem to remember using QGIS a while ago and finding California Zone 5 in my basket of CRS’s however this time around I am only finding NAD83 UTM 11. Is there a way to get back or download CRS for California Zone 5 of NAD83?
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