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I have photogrammetry DEM with 3 meter resolution. I need grid point with 30 meter resolution with the 3 meter accuracy.

Case-1, I created the the 30x30 meter grid points and extract the elevation from DEM.

Case-2, I interpolate the 3x3 meter DEM to 30x30 meter raster by using near neighbor interpolation.

Case-3, Create TIN from Raster and create raster 30x30 meter.

Could you guide which is the best method to interpolate high resolution to low resolution raster?

PolyGeo
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Shahid
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    If you clarify "best" with some kind of objective criteria, your question might be answerable. – alphabetasoup Nov 28 '19 at 21:56
  • I would use case 2 but how to do this depends on your software, case 1 you're just accepting where the point falls which could be noise, case 3 is just a long winded way of achieving case 2. You also need to carefully consider your resample algorithm, what metric are you trying to see in your DEM? Min, max, mean are all metrics which can be used to prove different things. From the raster you can create points by converting raster to point; how to do that depends on your software. – Michael Stimson Nov 28 '19 at 22:53
  • I just clear the purpose of this question, As I mentioned I have photogrammetry DTM 3x3 meter. It’s accuracy is 3 meter at 95% CL. I need to convert this DTM to 1arc second resolution grid points for airport eTOD data for area 2 which is 45 km in radius. The accuracy required also 3 meter at 90% CL. I am afraid if I use the interpolation may be a loose the accuracy. I am using ArcMap with spatial analysis extension for it. – Shahid Nov 29 '19 at 08:26

1 Answers1

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If I understand you correctly, your DEM is currently a 3x3 meter raster and you want a point grid, with points spaced 30x30 meter.

I would either go with case 1 or 2

Case1: Output will be a point file. With this method you will extract the elevation from the raster at the location of the point.

Case2: Output will be a raster file. Results depend on the interpolation method you choose:

  • nearest neighbor: extract the elevation from the raster at the center of the resampled raster cell. This is similar to case1 except that your output file is a raster.
  • average/max/min/mode: computes the average/max/min/mode elevation for all input pixels covered by resampled raster cell.

If you would want a point file as endresult you would then need to export your raster to points.

Thomas
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