Spatial Analyst is a extension within ArcGIS that provides a range of spatial modeling and analysis tools.
14
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5answers
2k views
Ways to Speed Up Python Scripts Running As ArcGIS Tools
This is a pretty general question. I just wondering what tips and tricks GIS programmers have used to speed up arcpy scripts that you import into the toolbox and run.
I work most everyday writing ...
14
votes
4answers
1k views
Where can I find examples of fuzzy logic applications in ArcGIS?
The last ArcGIS version (10) includes two arctoolbox tools for fuzzy logic (Fuzzy Membership, and Fuzzy Overlay). Does anyone know where can I find some examples showing how they can be applied?
...
13
votes
6answers
3k views
Methodology for creating accurate drainage networks (and catchments) from high resolution LiDAR DEM?
This is not the first time I've stumbled over this issue; it seems that I am unable to generate a correct drainage network model and the resulting catchments from full resolution (1m cells) LiDAR ...
9
votes
4answers
747 views
Are there any open source tools to detect and fill sinks on a DEM?
Are there any open source or inexpensive tools to detect and fill sinks on a DEM? ESRI Spatial Analyst is just out of my price range.
9
votes
2answers
339 views
How can I get weighted Flow Accumulation to deal with negative values? [duplicate]
here's one I haven't seen anywhere, to my surprise. I am trying to do something a little different with Flow Accumulation, which I would think has been attempted before, but it's stumping me for now.
...
8
votes
1answer
481 views
What type of kernel density function does ArcMap use?
I know that there are several types of kernel density functions, such as uniform, cosine, Gaussian, etc. I was just wondering which one the "Kernel Density" functionality in ArcMap 10's Spatial ...
8
votes
1answer
118 views
Are there any rules of thumb for the neighborhood settings in Focal Statistics?
In ArcGIS 10, users can define the neighborhood in the Focal statistics tool. The moving window shape can be set to any of the following: Wedge, annulus, circle, rectangle, irregular, and weight. ...
7
votes
5answers
1k views
What type of interpolation should I use to visualize metal detection survey data?
I have about 500,000 points collected in a linear grid pattern over a 1 km2 area. The points were collected as part of a metal detection survey. Each point has X,Y and Coil Response mV (min -675.38 ...
7
votes
3answers
713 views
How to cluster points based on a kernel density?
I have a large dataset with 36k points representing commercial land uses, each with a field containing the square footage. I have run a kernel density analysis on this dataset, producing a raster ...
7
votes
3answers
388 views
How do I create a raster randomly choosing a cell value from 2 or more overlapping rasters?
I'm using Arc 10. I want it to combine multiple rasters into one, always choosing randomly from the values of overlapping cells. I have an image that may explain this better:
7
votes
1answer
137 views
Calculating distance from points to different class in raster
I am looking for some advice on how to calculate the distance from a point to a different class of a raster. Specifically, I have observations (points) of animal use overlaid on land cover data. For ...
6
votes
7answers
2k views
Extract raster values at points
How can I extract values from a raster by points. I prefer not in Arcgis. I prefer in Qgis or Mapwindow or other open source gis.
6
votes
3answers
3k views
Clipping a raster using a polyline or polygon
I have a large raster created from values that cover the whole United States and Alaska which are both polygon and polyline features, this raster was caluclated using Spatial Analyst IDW ...
6
votes
2answers
722 views
Process a raster with multiple geoprocessing tools in arcgis 10 using python - flow between processes
I'm writing a short python script that includes processing rasters with different geoprocessing tools in ArcGis 10, for example, the three processes below, is this best way to use multiple tools ...
6
votes
1answer
181 views
Why does tool take longer to run when in Python script?
I have written a python script that does some euclidean allocation. For that I use arcpy.gp.EucAllocation_sa() method. Now, my python script takes 30-40% extra time than spatial analyst euclidean ...
6
votes
2answers
349 views
Recommend text for Spatial Analyst? (ArcGIS)
Does anyone have a recommendation for a good reference/tutorial(s) on Spatial Analyst? The most recent I can find are from early to mid 2000s. Or has SA simply not changed much in 7 years? Thanks, ...
6
votes
2answers
465 views
What are best practices to compare densities and locations between two sets of points?
I have two sets of point shapefiles. They represent two different customer groups for a retail store. Shapefile A represents online customers, Shapefile B represents in-store customers.
What I ...
6
votes
1answer
329 views
Problem analysing movement using cost surfaces (involving ArcGIS's Path Distance-tool)
I would like to analyse hypothetical movement (on foot) in a landscape as based on energy expenditure, but I have run into some trouble that I am hoping that you could help me with. I have tried to do ...
5
votes
2answers
674 views
Using an integer variable in where-clause in arcgis python script
I've seen some questions on this, but there seem to be many different answers... and none have seemed to work. I'm trying to include an integer variable in the SQL where-clause of a tool like this ...
5
votes
2answers
768 views
Can shaded relief be “blended” with DEM colour ramp in ArcGIS to produce a more visually dramatic result?
Not being able to use true transparencies with ArcGIS colour ramps where only solid colours are allowed has me always wondering about how to improve the look of the surface in my maps without ...
5
votes
1answer
206 views
How do I get the upstream distance to all points in a DEM from a single downstream point?
I want to get the upstream distance to all points in a DEM from a single downstream point. The goal is to create a "downstream distance to a point grid". This then would allow me to create "distance" ...
5
votes
1answer
5k views
creating a dem from contours
I have a large set of contours that I received broken down into several different subsets. I have merged most of the subsets together creating a larger set of contours in three different files. I have ...
5
votes
2answers
1k views
Viewsheds and Observer Points in ArcGIS Spatial analyst
I am trying to understand the viewshed and observer points tool in spatial analyst.
I want to show which areas of land can see a wind turbine, or put another way, from where can the wind turbine be ...
5
votes
3answers
299 views
Extract Overlapping Polygon Data to Points
I have a polygon data set of corn yield collected by a combine. However, as the combine drove through the field, there was slight overlap between passes, leading to overlapping polygons within the ...
5
votes
1answer
315 views
Extract Values to Point from Raster Issue
I am trying to use the tool Extract Values to Points on a File Geodatabase raster, but I am getting some weird errors.
I've used this tool multiple times before with no issue, but not since I ...
5
votes
1answer
226 views
How to find upstream - lateral and downstream zones around urban areas?
I've a DTM and a shapefile of built-up areas. For a fire risk model, I've to find (within a defined buffer zone) two zones around built-up areas: one that is above/higher and lateral and the other ...
5
votes
2answers
142 views
Monitoring programmes
I am not sure if it is a right place to ask this one but let me try.
Monitoring programmes are known for various targets and for various spatial levels.
They may include regions, countries or even ...
5
votes
2answers
86 views
Is there a way to increase the search radius of nearest neighbors for the Nibble tool?
I am working with a raster map vegetation types. I have about 20 types with unique raster code values that can be sorted into three classes:
1 - vegetation types I want to expand using the nibble ...
5
votes
1answer
267 views
How to calculate the flood volume using a LiDAR DEM and a HEC-RAS floodplain polygon
I’ve got a vexing GIS analysis problem which is
conceptually fairly straightforward, but in reality more challenging to figure out….
Basically, I need to calculate the VOLUME of floodwater within a
...
5
votes
1answer
432 views
Are special interpolation techniques required for weather data?
I've downloaded a series of weather observations from the local weather agency - it comprises around 1,000 points spread non-uniformly across Australia, with a greater density of points located near ...
4
votes
1answer
1k views
How do I add a hyphen to the Field Calculator to merge 2 columns?
I am trying to build a field calculator expression to merge two columns into one. I am looking for the word that makes it a range.
Example: I have 2 columns in elevation, From and To. I want to ...
4
votes
1answer
166 views
Work-around for slow processing times in ArcGIS 9.3 with Spatial Analyst functions
I am batch processing a large amount of distance functions (~50,000) using ArcGIS 9.3. In this version, using spatial analyst functions, it seems to be the case that users cannot parallelize processes ...
4
votes
2answers
535 views
Does a Zonal Statistics value change when applied on a subset of data?
I have generated zonal statistics using feature zone data on a value raster. This shapefile contains about 20000 polygons and the analysis went without a hitch.
While testing quality, I ran the same ...
4
votes
4answers
130 views
How to determine if all points on a map are identical in arcpy?
My eventual goal is to automate kernel density calculations for a large corpus of point data; however, if all points are identical (for example, if there are 7 points all stacked on top of one another ...
4
votes
2answers
4k views
NoData in ArcGIS Spatial Analysis
When using Spatial Analyst I regularly have issues with NoData values cropping up in the data. Various tools appear to introduce NoData values regularly. These values then cause issues with other ...
4
votes
3answers
500 views
Merging connected polygons (from raster cells)
I have created a polygon layer from rasters, and only have a single classification ID (and calculated acres) for each polygon. I would like to "dissolve" all touching features into larger, individual ...
4
votes
3answers
3k views
Find the nearest raster cell value based on a vector point
I have two layers in ArcGIS: One is a vector point and the other is a raster layer. I want to append the value of the raster data grid to the vector point. The problem is the vector point is away from ...
4
votes
1answer
620 views
How should I correctly exaggerate a hillshade raster (ArcGIS10, Spatial Analyst)?
I once wanted to generalize a high resolution raster and instead of MEAN i accidentally selected the default SUM technique, using a cell factor 5 (Lidar DEM is 1m resolution). When I used this result ...
4
votes
1answer
212 views
How to create a field with a specified slope projecting from a 3D polygon
Im trying to figure out how to create a elevation raster from a known location (3D polygon) that projects at a specified slope (1%) for a specified distance(1-2 km). Does anyone have any idea how to ...
4
votes
2answers
1k views
How can I compare two point shapefiles that contain lat/longs and compute distance?
Greetings everyone, I have 2 sets of point shapefiles in ArcGIS (group A and B), each set has around 1000 entries that contain lat/long. What I want to do is compare Group A against Group B and figure ...
4
votes
1answer
290 views
When merging two DEMs, do they have to be in the same pixel bits?
I have a simple question. I have 2 different Digital Elevation Modeling (DEM). One is the state DEM and has 30m and has 16 pixel bit. I have a couple of smaller DEM that has 30m but they have 32 pixel ...
4
votes
1answer
565 views
ArcMap 10 - Extract raster cells from imagery based on RGB value
I've got some aerial photography (format: IMAGINE Image) which is detailed enough to see to fire hydrants and a shapefile of fire hydrants which was digitized based on some CAD data. My project is to ...
4
votes
1answer
68 views
Sum raster data visible from given point, by proportion of view
I am wondering if there is a tool that does the following (preferably in Arc but other options considered).
Simple example: what proportion of the view from a given point on the landscape is occupied ...
4
votes
1answer
95 views
Raster Reclassify fails upon Completion in ArcGIS
When attempting to reclassify a raster in a student edition of ArcInfo 10, the program crashes without an error upon reaching 100%. The reclassified raster is written, but with no spatial info. I've ...
4
votes
1answer
259 views
Statistical analyses for survey against raster?
I am somewhat of a newbie to geostatistical analyses, but pretty
familiar with GIS and remote sensing packages. I was wondering if
anyone had suggestions on appropriate geostatistical analyses for a
...
4
votes
1answer
3k views
Thiessen Polygon delineation within a Feature
Greetings!
I am trying to create Thiessen (Voronoi) polygons, based on points within a defined shapefile extent.
The output should be inclusive to the feature. The output I receive now is the ...
4
votes
2answers
408 views
comparing two TINs
i have the following two files:
1) LiDAR las file1
2) Let's give it a name LiDAR las file2, contains the same file1 data, where number of points randomly removed.
So if file1 contains X number of ...
4
votes
1answer
170 views
Trouble Tabulate Area
I am using Kansas Cropland raster data from NASS with tabulate area to find out acreage of different crop types. The python I used works fine for 2006-2009 (56 meter cell size), except 2010 & ...
4
votes
1answer
911 views
Processing time using ArcGIS Hydrology toolbox tools in standalone Python script vs. ArcCatalog
My question is: what might cause the ArcGIS 9.3 Hydrology Toolbox Snap Pour Point and Watershed tools to run significantly slower in a
Python script versus manually running the tools in ArcCatalog ...
4
votes
1answer
76 views
How to calculate the volume of several DEMs to obtain elevation and volume changes?
I am trying to calculate the volume of several DEMs in order to obtain elevation and volume changes. I have pixels of 1x1 each one associated to an elevation. I used several methods but non of them ...
