Latest Contributions by MervynLotter

In 2012 (I cant recall which version of ArcMap, probably 10.1), I ran a Viewshed analysis on about 300 000 buildings and the process took 33 days to complete (805 hours)!  So it is possible, it just computationally intensive. Last year I ran a Visibility analysis on 17 716 points (as Input Points) and the process took just under a week to complete. Both of these analysis used the 90m DEM as input.  So I would think you need to reduce your number of inputs so best to subsample as Darren suggested. There is a geoprocessing tool called Generate points along line that you can use to create points every 100 m or so. It may be a good idea to use topography to inform the distance values for certain areas (more hilly, more points) but the trade-off would be that it then complicates the number of times a cell is visible (if that is of importance). ... View more

You can search using the *Locate *tool, and just add the list of layers (shapefiles or features) to search under Settings. Not quite as simple as ArcMap but I really like the search output. ... View more

If the source data is in point format, you could use the Extract Values to Points  tool to add the elevation value from your raster to your point dataset. Then simply add a column and use the calculator to subtract the two values. This would introduce less 'noise' through interpolation, particularly relevant if it may trigger an investigation. ... View more

Thanks George  ... View more

Have you tried the Feature Compare tool? Under Compare Type, you can select to compare geometry, attributes, etc., or just select all. I have used it to compare two large wetland datasets but admittedly I was not concerned about the attributes at the time.   ... View more

Have you seen this workflow for identifying highest (and lowest) points within a polygon using a DEM? Do see How To: Create points representing the highest or lowest elevations within polygon features  In step 1E, for "Statistics type", select "All", then you can choose which values you want to use in the workflow (min, max).  Summary "Using a Digital Elevation Model (DEM) raster and the Spatial Analyst extension, the location of the highest or lowest elevation can be identified for polygon features of interest. This procedure describes a basic workflow that generates a point feature class of the highest point within each polygon feature. In this example, highest elevations are used, but method this also works for lowest elevations." ... View more

I am sure there are other approaches that would work but the one I would try would be to create a new polygon feature class and then summarize your elevation values from your 3D polygon into this new polygon feature class. So you could start by creating a new polygon feature like a grid using the Create Fishnet tool, using your 3D polygon file as the Template Extent.  You will have to play around with size or number of columns to get the desired grid of approximately 10k polygons.   Then use the Summarize Within tool to summarize your elevation values into the new polygon file that you had created. Under Summary Fields, select your elevation field under Field and then Mean under Statistic.  I am not sure how long it woudl take to run on such a large polygon of yours, or whether it is even possible. I have never attempted something as large as this before.  ... View more

Eliminate works well for cleaning up data sets with small slivers. If I take a look at your images, then it looks like the size for each of your polygons would be almost identical, so therefore this may not be a good choice.  IF you had polygon attributes (do you?), there are other approaches for summarizing these values to into larger polygons. For example, one could create a grid or hexogons at the required scale across this data set, then use tools such as Summarise Within to populate the grid or hexagons with attribute data.  But this woudl only work in 2D, I am not sure whether your polygon is z enabled and you need it to stay that way.  ... View more

Sorry, just reread your message. I am not sure whether this tool will work on a 3D (multipatch?) polygon? ... View more

You may find that Eliminate or Eliminate Polygon Part tools can assist in cleaning up this data set.  Check out Eliminate Polygon Part—Data Management toolbox | ArcGIS for Desktop  or  Eliminate—Data Management toolbox | ArcGIS for Desktop . Unfortunately it does require an Advanced license. ... View more

Esri have just very recently released a geoprocessing tool, Locate Regions, that will assist in selecting the best areas from the output of a suitability or similar analysis. It is currently only available in Pro 1.3 but I believe it would also be available in ArcMap 10.5, due for release at the end of this year.  This tool is part of the Spatial Analyst toolbox. In the tool you can ask it to select the best site, or any number of best sites, of any given size, shape, distance from other best sites, etc.  It looks like a fantastic tool, do see Locate Regions—Help | ArcGIS for Desktop  and How the Locate Regions tool works—Help | ArcGIS for Desktop . ... View more

If you are not sure what the projection of your shapefile/raster should be, I find it is easier to include other shapefiles with a known projection (or an ESRI basemap) within your map view, and then change the projection of your map view until your unknown shapefile matches up perfectly with your background data, then bingo, you have your projection to use in the Define projection tool as Dan suggested. ... View more

Hi Rod Did you try running the Band Collection Statistics tool with computing correlation and covariance matrices option selected? It takes any number of rasters as input and I just quickly tested it on two input rasters (elevation and NDVI, not knowing whether it would run on only two rasters), and the resulting output provides that there is a 33% correlation for my example area. See below. # CORRELATION MATRIX # Layer 1 2 # -------------------------------------------------------------------------- 1 1.00000 -0.33215 2 -0.33215 1.00000 # ========================================================================== As Dan suggested, you could then use your DEM to create slope, aspect, depressions, topographical positional index, etc. and correlate these with your yield raster.  ... View more