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Thanks Dan. I thought I didn't have license access to ArcGIS Pro but apparently I do, so I am in the process of downloading it.
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03-10-2020
03:42 PM
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I don't seem to have this tool in my Data Management toolbox and doesn't come up with Search. Any idea why that might be? ArcMap 10.8 Desktop. Edit: OK, I think it is an ArcPro feature.
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03-10-2020
03:20 PM
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Splitting the line is not the problem, I need a method to actually draw the perpendicular segments.
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03-10-2020
03:03 PM
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I'm using ArcMap 10.8 Desktop I have a study region encompassed by a polygon (about 100km around - see attached). I converted that to a polyline, generalized and densified it to 1km segments (the light blue is the original polygon, the dark blue is the generalized line). If the line is converted to points (Feature Vertices to Points), it yields 129 points, about ~800m apart, which is about right (some fitting/equalizing occurs during Densify, I guess). I want to generate 1km transects along this generalized line (short segments perpendicular to and spanning the generalized line, occurring at regular intervals - see my hand-drawn red lines), presumably at the vertices. Any ideas on how to do this? There seems to be a tool that will do this with a route, but then my question shifts to "How do I convert this line to a route?" Thanks in advance.
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03-10-2020
02:35 PM
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One option is found here (pdf download) Modifying Digital Elevation Models to Develop More Realistic Wetness Index Layers for Soil Survey Applications By NRCS Soil Scientists Tom D’Avello, Joe Brennan, and Lynn Loomis
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02-07-2020
09:31 PM
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I am working with ArcMap and SAGA to run some hydrology functions on a region in Utah. The area I am looking at has a pretty gentle slope and I realized that a raised railroad bed is effectively "damming" the flow calculations. My interests are prehistoric, looking at alluvial fans in geologic time, so it is blocking the natural flow of sediment off the hill. I am using 30m DEMS and Focal Statistics to smooth the DEM out, before applying some of SAGA's hydrology functions. I'm looking for advice on how I might "remove" the railroad from the DEM. I can use the Focal Statistics Mean function smooth things out but the railroad is raised so much that the level of smoothing effectively blows out all the remaining terrain. I've attached in image to help get a sense of it. The black outline is the expected alluvial flow. My red hand-written lines are the flow direction and about where things get dammed up by the railroad bed. As you can see, the railroad unfortunately doesn't run in a straight line across the region. Thanks in advance. Dave
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02-06-2020
03:50 PM
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I am attempting to create a new, weighted raster from the combination of a regional DEM and a polygon shapefile. I've attached an image - the DEM is the background - the red/yellow region -- and the black polygons are from the shapefile. What I am attempting to achieve is a new raster where the cell values represented by the polygons are 1 and everything else is zero. I would like the new raster to have the same extent as the original DEM. I've tried a few approaches, using Clip to "cut" out the polygons and then Raster Calculator Con function to set various cells to zero but it seems very convoluted. Wondering if there is a cleaner approach? Thanks in advance. Dave
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01-31-2020
03:01 PM
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Thanks for the replies Duncan and Dan. Duncan, re. the "reappearing polygons" - in the process of replicating the steps to attach/demonstrate the issue I can replicate it (the polygons stay in the Attribute Table) but the only reappear when I choose a style of Hollow with an outline. If I choose a different Fill, all is good. This lead me to discovering I could also just delete rows in the Attribute Table (though 500+ was annoying) to get the single polygon I wanted. Dan, I will try your method with the raster directly and see if that is less work. Thanks.
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01-13-2020
02:36 PM
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I have a raster of an alluvial outflow (sediment running off a hill, see attached image). It is an integer raster and the flow is represented as 1s and non-flow as zeros. I am trying to create an efficient outline of the flow area. It could be a buffer or a single polygon that shows the extent of the 1s. I have tried converting the raster to polygons and using Eliminate Polygon Parts for a specified Area (eliminate polygons <1km2, for scale the flow is about 10km long). This initially looks correct, but ArcMap is not actually deleting the eliminated polygons (they are still in the Attribute Table) and if you change the style (like outline thickness) suddenly all the inner small polygons reappear (somewhat maddening). There is a similar bug in creating a layer by selection, where performing a style action brings back the unselected items. So, I'm open to other options. I am on ArcMap 10.5 and I have a spatial analyst license. Thanks in advance! Dave
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01-12-2020
02:25 PM
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Thanks Steve. I knew I was missing something like this.
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01-04-2020
01:14 PM
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I am trying to combine two rasters to create a weighted raster to use in some hydrology calculations. The first raster is a large region (a basin) in which I've set all the cells values to zero. The second raster was created from a set of small polygons that lie within the extent of the basin (the first raster). All the values within the second raster are set to 1. I'm trying to combine these two rasters into one raster that has the full extent of the first. When I use the Cell Statistics tool to Sum the rasters, the product raster is only the extent of the "polygons" from the second raster (basically a rectangle around the polygons). The values are correct (1 for the polygons and zero for everything else) but I want a raster returned that is the full extent of the first raster. The Cell Stats tools doesn't seem to allow me to choose an extent. I've attached an image to help visualize. The blue is the first raster (the basin). The red points are the "polygons" (raster 2), and the black rect shows the extent returned by the Cell Stats summation. I want the extent to be the full extent of the first raster (the blue). Options on other ways to achieve the same thing? Thanks! Dave
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01-04-2020
12:47 PM
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I'm trying to create an outline of a complex polygon. The polygon in question can be seen here (edit: I've attached the images below). This is an elevation model of an alluvial flow. As you can see, there are many little "islands" in the middle of the flow. I just want the greater outline of the flow, as demonstrated here (a poor hand-made outline in MS Paint...). For a sense of scale, this is about 10 km wide. The attribute table for the polygon only has a single row, so I can't just edit out the islands. I've tried Buffer, Dissolve, and Union, all basically end up looking about the same. Any advice on how to proceed would be appreciated. Thanks Dave
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12-21-2019
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rfairhur24, thanks for the detailed response. I suspected as much. I do want radii to vary based on a field associated with each point (population), so a Python script appears to be the way to go. Thanks for the overall outline. Dave
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07-27-2013
07:00 PM
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Hello, I am a new-ish ArcGIS user and this is my first post to the forums. Almost certainly, I am posting in the wrong place, but here goes. I want to create a buffer around points in a point shapefile, but rather than specify the buffer distance, I want to specify the area around the points and have the distance determined from that area (A = pi r**2, solve for r and use that as the traditional buffer distance). So, for example, if I had a point and specified that I want a buffer area of 1 hectare (10,000 sq mtrs), it would give me a buffer around that point of 56.4 meters. Is there an existing tool in ArcGIS that will accomplish this? Thanks in advance. Dave
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07-27-2013
04:01 PM
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