Hi
I would like to seek help in projecting my data to UTM WGS 1984.
DTM attached is in TIF file extracted from WorldDTM with GCS WGS 1984 projection while the other one is in shapefile extracted from CAD data (actual ground survey data) with PTM PRS 92 projection.
i followed the basic steps in reprojecting data but unfortunately i cannot execute it in the right way that it should be projected.
one of my objective is to convert the Shapefile to raster data so i can compare and calculate the difference of elevation in meters of these 2 topographic data.
Please help me on this matter. Attached is my data for reference.
Thank You!
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You have a number of issues with your data:
After you have assigned the correct projection Define Projection—Help | ArcGIS Desktop and have reprojected the data to be in the same projection as the DEM ( Project—Help | ArcGIS Desktop ) you can interpolate the contours Topo to Raster—Help | ArcGIS Desktop and calculate the difference between both DEM's Minus—Help | ArcGIS Desktop
ok thank you Mr Xander, i'll clean the data first.
Do you have any idea on what the correct projection for the contour lines might be?
Based on the lay out of CAD file, it is in PRS 92
Here's the screen shot of the CAD file legend
Just looked up that PRS## is for the Philippines. And it is based on the Luzon datum.
There are several zones with their own central meridians. So you need to know which zone.
And use the correct transformation between Luzon and WGS.
Too much detail I'm sure....
It falls within PRS Zone 4
I'm sorry it's zone 3
So currently the contour shapefile coord sys is defined like this :
But you can see from the extent tab, that this cannot be true.
Those numbers don't look like decimal degrees to me (too big).
So, redefine it like this:
Right click on the shapefile in Catalog (don't have it open in ArcMap at the same time).
Use the search to find "PRS", in projected coordinate systems.
Back in ArcMap, looking at the contour data with the online background imagery...
Changed the coord sys of the frame to :
Using this transformation :
Doesn't really fit with the imagery very well. But at this scale (quite large)...
When I overlay the river with the DEM you can see that it does not match at all.
Perhaps if the vector layer is flipped horizontally and vertically, rotated and perhaps enlarged is may come a bit closer, but you shouldn't do that:
This may be related to the coordinate system of one or both of the inputs and interpolate the contour lines followed by comparing both sources would not make much sense, since this will generate huge differences due to the mismatch of location.
Based on your output, what seems to be the problem? Is it the projection of DEM or the ground survey which is in shapefile?
For me it is difficult to compare these 2 since they have different baseline data, i mean different reference point.
Am I right?
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