Spatial Analyst is a extension within ArcGIS that provides a range of spatial modeling and analysis tools.

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17
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6answers
6k 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 ...
16
votes
3answers
676 views

Dealing with bridges and tunnels when modeling raster least cost paths?

I'm currently using ArcGIS 10 Spatial Analyst's Cost Path tool to model pedestrian routes. I have sidewalks, fences, buildings and a ton of pedestrian scale features, all combined into a cost surface ...
15
votes
4answers
2k 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
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6answers
6k 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 ...
13
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3answers
1k views

How does Nearest Neighbor Image Resampling work in ArcGIS?

I am trying to understand how nearest neighbor for the resampling of Image datasets works in ArcGIS. The output raster cell value is the value of the closest cell value in the input raster: In this ...
9
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4answers
1k 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
4answers
503 views

What Algorithm is used by ArcGIS Watershed tool?

Does anyone know what type of algorithm is used in the ArcGIS Watershed tool (in the Spatial Analyst package)? Very little information given on Esri's website ... but I suspect it may be some kind of ...
9
votes
3answers
624 views

Creating raster by randomly choosing cell value from multiple overlapping rasters?

I'm using ArcGIS Desktop 10 with its Spatial Analyst extension. How do I combine multiple rasters into one, always choosing randomly from the values of overlapping cells? I have an image that may ...
9
votes
2answers
667 views

Floodplain generation given river section polylines, flood level elevation points and a DEM of the land surface

I am looking to generate flood plain polygons to represent 20 and 100 year flood zones, in the most accurate and efficient way possible, given the following datasets: 1) River cross section polylines ...
9
votes
2answers
934 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
867 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
3answers
1k views

How to combine corner-touching polygons into a single feature

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 ...
8
votes
1answer
457 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 ...
8
votes
1answer
778 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 ...
8
votes
1answer
202 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
975 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
2answers
822 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 ...
7
votes
3answers
2k 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 ...
7
votes
2answers
1k 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 ...
7
votes
1answer
9k 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 ...
7
votes
3answers
218 views

How to compare spatial patterns (crime cases vs population)?

I am looking for a way to statistically compare two spatial patterns in shape polygon data (not point pattern analysis). Let's say I have a city map divided in neighborhoods (barrios), in shape ...
6
votes
7answers
3k 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
2answers
317 views

What do ArcGIS regression analysis warnings 000853, 000916 & 000981 mean?

I'm trying to do regression analysis using a shapefile which contains dependent variable (NDVI) and explanatory variable (prec) in ArcGIS. First, I run GWR analysis and then run spatial ...
6
votes
3answers
5k 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
1answer
2k 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 ...
6
votes
1answer
286 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
3answers
4k views

Finding nearest raster cell value based on 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 ...
6
votes
1answer
303 views

How to find nearest neighbors of polylines?

I have a shapefile containing irregularly placed polylines (i.e., survey routes). Following the general idea of a paper I read, I would like to use tessellation to identify the neighbors for each ...
6
votes
2answers
395 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
789 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 ...
5
votes
1answer
545 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 ...
5
votes
2answers
893 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
1answer
2k views

RMSE between two rasters step-by-step

Can anyone show how to calculate the RMSE (root mean square error) between following two rasters step-by-step and discuss on the obtained results' min and max values, and how to interpret it. Thanks a ...
5
votes
2answers
6k 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 ...
5
votes
1answer
422 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 ...
5
votes
1answer
75 views

Can I “stack” semivariogram data?

I have several synoptic measurements (every few months) of a gravity field I would like to interpolate by kriging. Each group of measurements comprises about 45 measurement locations, and spatial ...
5
votes
1answer
1k views

ESRI 3D Analyst: Which Graphics card?

in order to make the most of ESRI´s 3D analyst I would like to order an appropriate graphics card. I have been recommended the AMD FirePro V5900 2 GB by someone who doesn´t know much about GIS hence ...
5
votes
1answer
324 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 ...
5
votes
1answer
2k views

How to calculate stream order for vector data without a DEM?

I have a shapefile which contains the streams that were digitized from a satellite Image. I would like to calculate the stream order for this data. The data does not exactly match the DEM that I have, ...
5
votes
1answer
328 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
1k 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
3answers
2k views

Extract raster by mask output does not completely overlap the mask

I have a flow accumulation grid and a shapefile containing catchment areas. Now I want to do some calculations on them so I need to extract data from cells in the raster adjacent to certain catchment ...
5
votes
2answers
2k 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
2answers
44 views

Compare slopes between adjoining line segments

Using a DEM, I assigned slope values to individual segments in a street network feature class. In some areas the slope values seem suspect, such as where a highway overpasses a local road. Is there a ...
5
votes
2answers
203 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
179 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 ...
5
votes
1answer
340 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
149 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
1answer
1k 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 ...