Tagged Questions

Raster is a data format consisting of regular grids of values, usually stored in an image-like format.

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2
votes
1answer
113 views

Can Identify tool to return the raw values of rasters?

I have a raster in ArcGIS 10 SP4 set to bilinear resampling in its display properties. When using the identify tool it returns the resampled value instead of the raw value. Can we get the identify ...
1
vote
1answer
409 views

OpenLayers ArcGIS Image Service Support

i have ArcGIS Image Server for publishing my raster data to my user. In traditionally way i have been tiling with gdal and it takes a long time besides this it requires more effort for getting true ...
0
votes
1answer
173 views

Progress bar percentage is increasing and decreasing, never finishing

I am trying to clip a raster by shapefile perimeter using the Clip tool. The percentage has been jumping between 0% and 100% for over an hour, back and forth, climbing to 100% then dropping down to ...
7
votes
7answers
2k views

how to overlay shapefile and raster?

I have a shapefile with polygons. And I have a global raster file. I want to overlay the shapefile's polygons onto the raster grid and calculate the mean raster value for each polygon. How can I do ...
3
votes
3answers
319 views

ArcGIS 10 Raster Mosaicing versus Lizardtech Express Server

Trying to determine if I still need to use Lizardtech Express Server to mosaic rasters together or just use the Mosaic Raster Dataset function of ArcGIS 10? I know for earlier releases of Express ...
3
votes
1answer
1k views

How to split a polygon into multiple small parts by grid

we delineated a river basin in shape file and generated a line-featured shapefile using Hawths tools. now our task is that we want to divide this basin into small polygons by gird in order to compute ...
1
vote
1answer
131 views

ESRI ISurface.GetElevation is extremely slow compared to GlobalMapper

I'm using ISurface.GetElevation on a Raster to get the elevation for a specific lat/lon. I have to do this for a huge set of datapoints. Currently i'm testing with a dataset of 10.000 items which ...
4
votes
1answer
206 views

How to change field name in raster file?

I´m having a bit of an understanding problem with a DEM TIF file. I have a DEM TIF file which is served with Geoserver. When I click on the layer the WMSGetFeatureInfo gives me the following output: ...
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 ...
0
votes
1answer
244 views

What is the easy way for extracting a dted raster file?

i have some srtm data which was converted to dted file with globalmapper or arcmap ascii to raster. i want to extract raster from vector with easy way.. i have tried "extract by mask" method but it ...
5
votes
1answer
3k views

Calculating distance to points in QGIS

Is there a way of calculating the distance to the nearest points in QGIS? In ArcGIS there is a function called Euclidean Distance, which can take an input vector or raster, and generate a raster of ...
2
votes
1answer
744 views

Conversion of raster features to polylines: skeletonization?

I would like to identify linear features, such as roads and rivers, on raster maps and convert them to a linear vector features (i.e. polylines). I typically use R as my primary GIS, and have posed ...
2
votes
2answers
2k views

Raster Combine - ESRI Spatial Analyst

I am trying to combine a whole bunch of rasters with Esri Spatial Analyst. Seems to be doing what I want EXCEPT the calculated output is only the area where all 4 rasters overlap. I am a complete ...
2
votes
2answers
873 views

GDAL Clipping (hack)

I am trying to use the python script from http://www.sparkgeo.com/labs/2010/07/07/gdal-clipping-hack/ to clip a raster based on many shapefiles. The script is using a mysql database an i would like to ...
9
votes
1answer
362 views

Efficient raster sampling of billions of polygons (bounding boxes)

How can a raster be computed efficiently (in Python), given a set consisting of billions of bounding boxes (read sequentially from a file), and given that the raster values for each cell should give ...
2
votes
1answer
158 views

Why is GRASS not thinning a terraflow raster properly?

I want to convert a raster map encoding directional flows (the output of r.terraflow) to a vector map. I'm using r.thin to process the output. It terminates successfully with 0 pixels removed during ...
3
votes
1answer
367 views

Looking for Mid-Holocene (~6000 BP) bioclim dataset

I am trying to obtain climate data for the Mid-Holocene (~6000 BP), preferably in the bioclim (19 bioclimatic variables) raster format. The worldclim.org website lists this dataset based on the CCSM ...
2
votes
1answer
2k views

Why is ArcGIS crashing when I try to load .adf raster data?

I am pretty new to GIS, so forgive me if this is a stupid question. I downloaded a bunch of land cover files from USGS seamless warehouse of Florida. Every time I try to 1) view the .adf file (which ...
3
votes
1answer
288 views

ArcSDE - How to edit mosaic dataset

I have a mosaic dataset (Raster) in an SDE database. As expected, when I click start editing, ArcMap says that I have to do "Register as Versioned" before, but I can't have a mosaic dataset in a ...
2
votes
1answer
579 views

Select vectors overlapping a raster

I have a raster layer with travel times from a specified point in my city's downtown. What I'd like to do is select all of the census blocks that lie at least partially within 45 minutes of downtown ...
0
votes
3answers
408 views

Adding .bil raster file to GeoServer and viewing it on GeoServer or GeoNode

Ok so my Boss gave me this job. Uptil now i was working on ESRI products and this is my first venture into OpenGEO. He has given me a link, http://www.worldclim.org/current, from where i need to use ...
5
votes
0answers
286 views

How to store Large Raster Images of Equipotential Surface Generation Using Monte Carlo Simulation?

I have a large (1GB+) raster that I am using as the base for the generation of an equipotential surface. This is to assess the accuracy of DEMs derived from another source. In situ observation is ...
2
votes
1answer
811 views

QGIS and satellite images band combination

When I add a satellite images as a raster in QGIS: 1. Why the image is changed, it looks like it has only one band?; 2. where is a tool for band combination? Thanks!
7
votes
6answers
14k views

How to get X Y coordinates and cell value of each pixel in a raster using Python?

I’m really new to Python and I would like to know whether there is a quick method to get cell values of a raster pixel by pixel and the coordinates (map X Y coordinate of centre of each pixel) using ...
1
vote
0answers
677 views

ArcGIS 10 - disappearing rasters?

From time to time it happens to me that rasters disappear at certain zoom level in ArcMap, or only some parts of the raster (strips) show up. I'm working on WinXP, ArcGIS / ArcView 10, Sp2, rasters ...
3
votes
1answer
135 views

rgb2pct.py increases size of file 20 fold!

I wanted to reduce the number of bands of a tif file from 3 to 1... I used this command rgb2pct.py -n 256 fnp_braunschweig.tif fnp_bs.tif and it increased the size from 31mb to 778mb I actually ...
5
votes
2answers
2k views

Using individual bands from a multi-band image in ArcGIS 10 raster calculator

I'm trying to use individual bands from a multi-band TM image (IMG file) within the raster calculator in ArcGIS 10 (SP2/3). I can add individual bands to my MXD, but raster calculator will only use ...
2
votes
0answers
237 views

how to buffer a raster cell using Visual Basic ArcObjects in ArcMap [closed]

I am new in visual basic, I have a question about creating a buffer zone based on a raster layer. I have a raster layer named "Value_Raster", I have a textbox in the userform, I also create a tool ...
1
vote
1answer
668 views

1-band raster colour table workaround in QGIS

Does anyone know what the workarounds are for the 1-band raster colour table plugin in QGIS? Currently I find it will run once, then crash on the second iteration. The workaround I use is to delete ...
1
vote
0answers
189 views

How can I ignore NoData values in map algebra? [duplicate]

I need a way to exclude NoData from calculations. I don't want any NoData cells from any of the rasters to be used in pick or con statements.
7
votes
3answers
2k views

Poor image quality of raster pyramid files in ArcGIS (no anti-aliasing)

There are several GeoTIFF files (size ~7000x7000 px) which I try to open in ArcGIS Desktop 10.0. I have already created raster pyramids for them (.ovr files) using geoprocessing tool but their quality ...
7
votes
2answers
998 views

How to animate raster time series using open-source GIS?

I have a bunch of rasters taken about 10 minutes apart, and I have a nice QGIS project that produces pretty enough maps of them. I'm wondering if there's a way to animate this raster series, with a ...
5
votes
2answers
2k views

Using SearchCursor to access & export values in a raster table

I am desperately trying to export the values in a raster table to a .txt file. I've seen some other folk post about this, but for some reason can't get the code to work in my case. I have a raster, ...
2
votes
1answer
506 views

Spatial Analyst tool Look up but in ArcView3.2

Is there any option how to do a Spatial Analyst tool "Look up" operation from ArcGIS 10 in ArcView 3.2? I have a grid with attributes and need to "extract" values from the table field (values from ...
1
vote
0answers
48 views

How to recreate the 'standard deviation' option for a raster layer in Mapserver?

In mapserver is there any way to recreate the 'standard deviation' option available in Arc's symbology for a stretched raster layer?
0
votes
3answers
127 views

How to add a float or integer number (i.e 255) to a raster layer?

Is there any code to add a float or integer value with a raster layer? I can easily do mathematical operations between two raster data. But I am unable to do the same between float or integer number ...
4
votes
1answer
983 views

Why does QGIS's Clipper tell me “Computed -srcwin falls outside raster size” and how do I address it?

I'm trying to clip a heightmap to a small area that I'm interested in. When I attempt to use Raster > Extraction > Clipper I get an error dialog with the message ""Computed -srcwin falls outside ...
6
votes
2answers
1k views

creating a raster of the residuals of a regression between two rasters

I am trying to create a raster of the residuals of a regression between two rasters. i.e. I would like to carry out a regression of one raster against another of the same extent and plot the residual ...
15
votes
2answers
5k views

How can I convert data in the form of lat, lon, value into a raster file using R?

I have a data set of values over a km grid in the continental U.S. The columns are "latitude", "longitude", and "observation", e.g.: "lat" "lon" "yield" 25.567 -120.347 3.6 25.832 ...
1
vote
1answer
1k views

How to create a single depth contour line from a bathymetric raster?

I have bathymetric data (raster form) that I'm trying to tease out specific depth contours. For example, I would like to "create" the 150-m depth contour from the bathymetric data in the Gulf of ...
2
votes
2answers
369 views

Mapinfo, (or other?) Interpolation of lat/long and finding minimum in a region

I have a series of lat/long coordinates, each with a corresponding Z value. Each coordinate is spaced roughly 40km apart (this is stored as a MapInfo table of points). What I'd like to do is to ...
9
votes
3answers
680 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 ...
10
votes
2answers
2k views

Intersecting a raster with a polygon using PostGIS - artefact error

I'm using PostGIS2.0 to do some raster/polygon intersections. I'm having difficulty understanding which operation I should use, and what the quickest way of performing this is. My problem is as ...
6
votes
2answers
398 views

Confidence interval from raster data

I have raster data that represents a probability distribution, i.e. each cell has a probability value (in my case the probability that an animal may be found in the cell), and all the cells add up to ...
4
votes
3answers
367 views

Export from GIS to static html clickable hypermap?

What plugins or tools are available to conveniently export a GIS view to a html clickable hypermap? Since 2005 or so we use a commerial plugin for ArcGIS, We have a working example of the output ...
1
vote
1answer
637 views

Help with technique to create contours from ASTER DEM in Phnom Penh, Cambodia

I have the ASTER version 2 DEM of Cambodia. I want to use it to create 1m contours of Phnom Penh, Cambodia. If anyone has this already please let me know. Now, onto the problems: I am using ArcGIS ...
4
votes
2answers
533 views

How to generate an image from WKT?

I am looking to programatically generate an image from a WKT string (or any other common format, such as WKB or SQL Spatial geography). Are there any existing libraries that allow for this? I am ...
2
votes
1answer
475 views

SUM Area irregular polygons per grid cell

I have a shapefile of irregular polygons and a GRID (both as raster and polygon grid). How can I count the AREA SUM of irregular polygons per grid cell? Can use ArcGIS, QGIS or R. (Application: ...
3
votes
1answer
437 views

How can I apply a raster style to multiple layers using MapServer?

I'm using Mapserver to display a raster in browser using a WMS request from OpenLayers. At the moment I have just one raster, and used the following method of styling it: MAP ########### ...
3
votes
1answer
506 views

turning multiple vector layers into one raster in arcgis 9.3.1

I want to make a raster out of the multitier view I have in ArcMap 9.3.1 . The layers in my ArcMap come from several datasets. I know there is a 'Feature to Raster' tool, but it converts one layer at ...