Latest Contributions by DavisTolman

‎02-18-2020

I have had some success in predicting flood risk by building a "residual surface" from detailed LIDAR data. I construct a smoothed surface across the watershed (often a 7th to 10th order polynomial surface) and then subtract the original detailed terrain surface, leaving the residual. This surface provides a great visual representation of drainage systems across a broad area. Rather than using a sampling from the entire terrain data set, I'd like to try using just the axis of the drainage systems. My hypothesis is that it may be even a better predictor. I've have been working in ArcMap and ArcGIS Pro.

‎02-18-2020

I will then create a regional surface that corresponds to the stream-bed elevations. I've thought of converting the flow-lines into a series of points, sampling the terrain at these points and then using one of the geostatistical tools to create a "smoothed" surface from these points. Anyone have thoughts on how to best accomplish this this?

‎03-18-2019

DRA is a great real-time visualization tool. Is there any way to get DRA to work for terrain files when using a 3D Scene? Also, why doesn't the legend scale bar adjust for the DRA range when viewing a map in ArcGIS Pro (like it does in ArcMap)?

‎03-18-2019

Open up your color scheme selection. At the bottom is "format color scheme" button. There is a symbol on the next screen to flip the colors.

‎10-06-2017

I've tried calculating statistics for this DEM, but the layer properties still says that no statistics have been calculated. Is there something wrong with my raster or am I missing something else. Below is what my Zonal Histogram table looks like. Rather than showing the rows as feet (elevation), it shows a objectid column instead. I'm pretty sure that the values within the polygons represent the elevation distribution for that polygon, but the units are not apparent.

‎10-05-2017

Thanks, I'll calculate statistics and retry.

‎10-05-2017

No statistics have been calculated... do I need to do this?

‎10-05-2017

Is this helpful?

‎10-05-2017

Thanks, Python and Matlab are both tools that I would like to learn someday.

‎10-05-2017

Thanks for responding. Actually I did try Sample.... but but I'm wanting to compile All of the elevation points within a polygon. What I'm trying to do is to represent the dem elevation values within a polygon in 2-dimensions. Sample is fine for points but I'm looking to represent area in an "elevation histogram" or frequency plot. Any suggestions on what tool to use for this?

‎10-05-2017

I have a lidar DEM model of the Houston area floodplain with polygons representing areas protected by levees. I would like analyze the elevation within each levee by sampling the elevation values within the polygons and representing them as a histogram or frequency plot. Ideally, the x axis would be binned elevation and the y axis would be the frequency (count). I've tried the Sample Tool from the spatial analyst toolset, but instead of obtaining the elevation values, I seem to be getting a number between 1 and 256 (...the display value?)

‎10-07-2016

I tried again using he correct zone field and it worked. THANKS VERY MUCH! Davis

‎10-07-2016

Thanks Chris, I tried this and created a raster with the shape of the subdivisions that assigned a single average value for the entire raster, not the average for each separate polygon. Ideally, I would like to extract the average value for each polygon and add it as a field in the subdivision shapefile. Any thoughts? Davis Tolman

‎10-06-2016

I have a raster file (elevation) and a shape file (neighborhood polygons). I would like to sample the raster for each polygon and assign the average raster value to its' respective polygon. Ideally I would add a new column with the average elevation for each row in the shape file.

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Date Last Visited	‎12-29-2023 02:43 PM

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Latest Contributions by DavisTolman

Re: I would like to sample terrain elevation values along stream-beds.

I would like to sample terrain elevation values along stream-beds.

DRA not working correclty

Re: Invert color scheme for stretched rasters in ArcGIS Pro

Re: Create a frequency plot for raster elevation values with in a polygon

Re: Create a frequency plot for raster elevation values with in a polygon

Re: Create a frequency plot for raster elevation values with in a polygon

Re: Create a frequency plot for raster elevation values with in a polygon

Re: Create a frequency plot for raster elevation values with in a polygon

Re: Create a frequency plot for raster elevation values with in a polygon

Create a frequency plot for raster elevation values with in a polygon

Re: How do I assign average raster values to polygons within a shapefile

Re: How do I assign average raster values to polygons within a shapefile

How do I assign average raster values to polygons within a shapefile

How do I assign average raster values to polygons ...

Re: Invert color scheme for stretched rasters in A...