All Questions
1,891 questions
31
votes
7
answers
19k
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 data....
- 20.4k
30
votes
6
answers
23k
views
Ways to Speed Up Python Scripts Running As ArcGIS Tools [closed]
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 ...
- 4,387
25
votes
3
answers
48k
views
Merging multiple SpatialPolygonDataFrames into 1 SPDF in R?
I have created 2 polygons in QGIS. Using them in R, polygons become automatically SpatialPolygonsDataFrame (SPDF). I would like to merge them into single SPDF (as is super easy in ArcGis using Tool ...
- 3,386
25
votes
3
answers
2k
views
Counting consecutive pixel values for set of rasters using ArcGIS Spatial Analyst?
I'm using ArcGIS 10 with Spatial Analyst.
I have a set of rasters (8 in total) that only every contain a 1 or a 0 for each cell. Each raster represents a different years worth of data. For arguments ...
- 44.6k
22
votes
3
answers
1k
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 ...
- 221
17
votes
2
answers
12k
views
Seeking QGIS equivalent to Focal Statistics of ArcGIS Spatial Analyst?
I'm attempting to use QGIS v2.0.1 to accomplish the same tasks that I can do using ArcMap v10.1 and I'm running into some trouble finding equivalent tools. In ArcMap I am using the Focal Statistics (...
- 253
16
votes
3
answers
7k
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 ...
- 2,546
15
votes
1
answer
20k
views
Is Clip (Data management) or Extract By Mask (Spatial Analyst) more efficient?
I'm trying to clip down an Orthophoto to a county boundary. I've been using the Extract By Mask Tool, but this process has been running for about 12 hours! It's gone through 2 cycles already, so I'm ...
- 451
15
votes
4
answers
5k
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?
(...
- 151
14
votes
3
answers
13k
views
Finding locations of highest values in raster using ArcGIS Desktop?
Using ArcGIS 10, I have a raster where I would like to find the pixel with the maximum value in the raster and return its location (center of pixel) in decimal degrees. I would like to iterate through ...
- 165
14
votes
4
answers
5k
views
Combining 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 ...
- 23.2k
12
votes
2
answers
54k
views
Creating DEM from contours using ArcGIS Desktop?
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 ...
- 239
11
votes
1
answer
1k
views
Cube root on ArcGIS raster calculator?
How I could extract a cube root of the multiplication of 3 rasters in raster calculator?
Eg: cuberoot (ras1 * ras2 * ras3)
11
votes
2
answers
8k
views
How to calculate stream order for vector data without a DEM? [closed]
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, ...
- 41.6k
11
votes
0
answers
2k
views
Why is GDAL ECW compression much poorer than ECW compression from ERDAS [closed]
We use ECW compressor shipped with ERDAS Imagine to export Orthoimagery for our different departments. Because we are facing problems with the Imagine license server, we had to choose GDAL (built with ...
- 1,643
11
votes
0
answers
1k
views
What is the convergence threshold for ArcGIS Iso Cluster?
The ArcGIS tool Iso Cluster Unsupervised Classification does not seem to have any documentation on the convergence threshold used in the tool. To compare, Erdas Imagine has all of the necessary ...
- 51.8k
10
votes
5
answers
12k
views
How to workaround large mosaic process which is failing?
I need to mosaic about 550Gb of tif imagery together and the software I have tried keeps failing. The area has been split into zones so that the smallest has approx 200 tiles.
I have used the latest ...
- 8,298
10
votes
4
answers
35k
views
Filling NoData gaps in raster using ArcGIS Desktop?
I have a raster with gaps in it. I want to fill these in with averages of surrounding cells using ArcGIS 10.2 for Desktop.
I have tried "Focal Statistics" but it averages EVERY cell and not just the ...
- 101
10
votes
4
answers
5k
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 ...
- 2,298
10
votes
3
answers
12k
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 ...
- 2,215
10
votes
1
answer
36k
views
Extracting specific values to new raster in ArcGIS Desktop?
I have a map with data stored in file geodatabase (gdb) format. As I opened it in ArcGIS 10, I see that it has data for 12 years, each year encoded in different color.
How do I create 12 different ...
- 103
10
votes
3
answers
6k
views
Remove clumps of pixels in R
I would like to remove isolated pixels (or clumps of pixels <9) from my raster image.
library(raster)
# create some raster data
r <- raster(ncols=12, nrows=12)
set.seed(0)
r[] <- round(runif(...
- 3,386
10
votes
6
answers
7k
views
NoData values recognised in raster in ArcGIS Desktop but not following symbology rules?
I have a GeoTIFF raster in ArcGIS Desktop, which can be downloaded from the following two links:
http://www.rtwilson.com/downloads/MODIS_MOD04_16-06-2006_Subset.tfw
http://www.rtwilson.com/downloads/...
- 4,014
10
votes
3
answers
1k
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 ...
- 101
10
votes
3
answers
2k
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 ...
- 1,171
10
votes
1
answer
2k
views
Calculating distance from points to different class in raster using ArcGIS Spatial Analyst?
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.
...
- 155
10
votes
1
answer
9k
views
Reassigning raster cell values from another attribute in raster attribute table?
I have a large (size of lower 48 U.S.) 100m resolution raster dataset that has a raster attribute table (RAT). The data were created by someone else. One of the attributes in the RAT has the data ...
- 1,127
10
votes
2
answers
11k
views
Dealing with NoData in ArcGIS Spatial Analyst?
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 ...
- 6,127
10
votes
4
answers
1k
views
Raster smoothing using ArcMap
I need to simulate a debris avalanche, but in my elevation raster the avalanche deposit is included so I'd need to take it off to simulate on a pre-avalanche-like surface.
Unfortunately the only data ...
- 939
10
votes
1
answer
2k
views
How to Remove Dark Bands Where Scenes Overlap in Mosaic Landsat TM5 Image?
I have an image mosaic of 5 Landsat TM5 scenes. Where the scenes overlap there is a dark band, only on the left and right sides, but the top and bottom are seamless. What is the best way to correct ...
- 101
9
votes
5
answers
35k
views
Converting raster file from float to integer type in ArcGIS for Desktop?
I have a float type raster file (an NDVI made from ERDAS IMAGINE) and would like to convert it to an interger type raster file in order to use Focal Statistics function (Majority). Is there any way to ...
- 111
9
votes
1
answer
9k
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 them.
...
opl
9
votes
2
answers
3k
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 ...
- 465
9
votes
2
answers
9k
views
Specifying field in attribute table with raster calculator using ArcMap
How can I specify the attribute field to use in the raster calculator of ArcMap 10.2?
In 9.x, I used the dot notation.
i.e. To use the "New_Value" field, I could do the following:
[MyRaster]....
- 1,455
9
votes
1
answer
14k
views
Extracting raster cells from imagery based on RGB value using ArcGIS Desktop?
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 ...
- 526
9
votes
1
answer
523
views
Confidence in pan-sharpened classification?
I pan-sharpened one Landsat Image on ERDAS using the resolution merge resource, with brovey transform and nearest neighbor techniques. But I was told that in terms of land-use classification, it would ...
- 91
9
votes
1
answer
2k
views
Analysing movement using cost surfaces with ArcGIS 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 ...
- 143
9
votes
2
answers
4k
views
Generating floodplain generation given river section polylines, flood level elevation points and DEM of land surface? [closed]
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:
River cross section polylines
...
- 1,867
9
votes
1
answer
1k
views
Any rules of thumb for 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. ...
- 51.8k
9
votes
2
answers
2k
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.
...
- 537
8
votes
2
answers
9k
views
How do you identify ridges on an elevation raster?
I was wondering whether anyone might be able to tell me in layman's terms how to extract or differentiate between ridges and hilltops from 10m elevation data using ArcGIS 10.1?
- 81
8
votes
4
answers
19k
views
General steps to create watershed boundary in ArcGIS Spatial Analyst?
I am an ArcGIS beginner.
I have a CD of GIS files of a city and intend to work on watershed management.
There are different file names in different formats on CD. Like .shp, .shx, .dbf, .sbx. and ...
- 83
8
votes
2
answers
9k
views
How get intersection of polygons in the same table by PostGIS?
I have a single table of over 1000 polygons in postgreSQL (with PostGIS), and I have a field "evaluation_type" that only receives two values, either 'good'(green) or 'bad'(red), as you can see in the ...
- 194
8
votes
2
answers
14k
views
ArcGIS ERROR 000824: The tool is not licensed in arcpy
I try to run the Zonal Statistic as a Table through ArcPy and it gives me:
ERROR 000824: The tool is not licensed.
Here is the doc for the function: http://resources.arcgis.com/en/help/main/10.1/...
- 141
8
votes
2
answers
4k
views
Creating point at highest value in raster using ArcGIS Desktop
I am using ArcGIS Desktop 10.1.
I am trying to find the location of the highest value pixel in my Direct Solar Radiation Raster. I can see the extent of the data in my raster but don't know where ...
- 869
8
votes
2
answers
2k
views
What is the Pick tool in ArcGIS's Spatial Analyst commonly used for?
I have recently encountered the Pick tool in the Spatial Analyst of ArcGIS. I understand what the tool does; it creates an output raster using a list of input rasters and a 'position' raster which ...
- 11.1k
8
votes
1
answer
5k
views
Making new raster using con() script and ArcPy
I'm new to Python and have been trying to code a raster calculator style script. Basically, I want to convert a raster that has values 0 to -10,000 into a raster that is populated by 1s between ...
- 83
8
votes
1
answer
2k
views
Changing class of one pixel in classified image
I have a classified image (I did it in ERDAS) with six categories. There are some misclassified pixels (especially high-density urban category).
Is there any way that I can choose one pixel and then ...
- 137
8
votes
3
answers
18k
views
Load a raster file directly in Leaflet
Is it possible to load a raster file (e.g. GeoTIFF or Erdas img) directly into a Leaflet map? If so, can you guide me to the correct documentation or method to do this?
I am trying to do this with the ...
- 529
8
votes
3
answers
6k
views
Extract raster by mask output does not completely overlap 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 ...
- 4,938