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Point To Raster - misaligned cells in output

Question asked by ckalinsk_USCSSI on Nov 18, 2018
Latest reply on Nov 20, 2018 by ckalinsk_USCSSI

When I generate a raster with Point To Raster, I am seeing odd shifts in the raster cell locations. I overlayed the original points with the raster. Across the northern and southern regions of the extent, the original points are centered north/south in the raster cells. They become less and less centered as one moves toward the middle of the extent relative to north/south. East/west there is no variation across the extent. They are centered east/west across the extent. There is a one cell wide band across the middle of the raster that has no cells with NoData values. It looks like the cells "drift" out of alignment as you approach the middle band of the extent.

 

What is also odd that I get the behavior when I start and end my processing (steps below) with a 1km resolution DEM but do not get the behavior with a 30m DEM. Images in the attached PDF for reference. Am I doing something off here? Any idea what is off in my data or work flow?

 

I have looked at the thread here: point to raster point is not in the center of the created cell

Not sure how to apply the other advice given there as I am seeing a different shift across the extent of this problem raster. This is a regular grid of points, so it seems confusing that the raster cells shift.

 

Work sequence:

1) Clip DEMs to study area. Roughly 100km east/west by 200km north/south. 

2) Use Raster To Point to create a regular grid of points from the raster. Examining these points show them centered on the cells.

3) Use Add XY Coordinates on point feature. (Need lat/long for climate model processing.)

4) Use Table To Table to generate a CSV file.

5) CSV file is used as input into the ClimateWNA program.

6) ClimateWNA outputs a CSV file with ~23 climate attributes for each point supplied. Output includes the original lat/long/elev. The program does not change these three values.

7) Use XY Table To Point to create a feature layer. Examining these points, they are centered on the cells in the original clipped DEM.

8) Use Point To Raster to create a raster for each of the needed climate attributes. One raster per attribute. The environment parameters for GCS, snap raster, cell size, and extent were all set to match the original DEM in step 1.

 

Step 8 is where the odd behavior described shows up. The work sequence using the 30m DEM has no issues with the offset. I have scanned across the same regions in the extent. Everything aligns: extent, cell size, points centered in cell. Even all the features and rasters with the 1km DEM align until the P2R step.

 

All GIS processing is with ArcGIS Pro 2.2.4 on a HP Windows 10 Pro desktop. ClimateWNA is a desktop program that is the source for the climate data attributes.

 

All features and rasters verified as being NAD83 GCS. ClimateWNA outputs in WGS84, but points projected to NAD83 show no delta in location. Raster issues appears whether the points are NAD83 or WGS84.

 

The north/south dynamics make me suspect some kind of projection issue. I tried combinations leaving various environment settings at default (other than cell size) but get the same odd behavior. ClimateWNA output was also suspect, but the points generated from that data align fine with the original DEM.

 

I am massaging data for eventual export into a MaxEnt environmental niche model. The two DEMs are a USGS 3DEP 1arc-sec (~30m)  acquired from the USGS site and PRISM's 30arc-sec (aka 800m aka 1km) DEM downloaded from their site. The PRISM data source is a USGS NED 3arc-sec DEM interpolated to resolution per their literature.

 

I need all the rasters generated at each resolution to align exactly in extent and cell size for the MaxEnt processing. They eventually get output as ASCII files and moved into an R workflow. I have done this workflow before with other USGS DEM datasets and had no issues. First time using the PRISM DEM however.

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