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

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1answer
174 views

How to stack rasters for ecological analysis?

The attached image shows two different forest openings. Each opening has the following layers associated with it: Point shapefile 1 = A red X which represent a large "legacy" tree in the gap Point ...
8
votes
6answers
1k views

Finding minimum bounding extent of given pixel value within raster?

I am wondering if there is a way to find the minimum bounding extent for a raster with a particular value. I clipped a raster from a global image and the extent is set as the global extent with a lot ...
9
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2answers
3k views

How to reclassify a very large land cover dataset?

Consider the NLCD2001 Land Cover dataset for Alaska (download link). I need to reclassify this dataset so that only pixels of value 41, 42, and 43 are preserved; all other pixel values should become ...
14
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3answers
417 views

Is it possible to use symbols instead of colours to visualise raster cell values?

I have a raster image (GeoTIFF) with integer values. I know how to visualise raster values in QGIS using colormaps or similar, but I would like to assign symbols to each colour value instead - just ...
7
votes
2answers
783 views

How to perform enhancement operations on an satellite imagery in QGIS?

I am a new user of QGIS please suggest how to perform image enhancement operations on an satellite imagery like ratioing, contrast stretching, edge engancement, filtering etc. in QGIS?
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0answers
229 views

How to rename .met file with model builder which uses an iterator to rename .sid files?

I have a model that iterates through a folder containing .sid raster datasets, amongst other types of rasters (so I'm using a *.sid wildcard). I note, however, that ArcCatalog/Model Builder/Rename ...
5
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3answers
3k views

Reproduce raster with same extent, and same number of columns and rows?

I have two raster A and B. A and B have the same grid size but different extent. How can I make A have the same number of columns and rows, as well as the spatial extent of B?
5
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1answer
2k views

How do I average a set of rasters?

How do I average a set of rasters? I have remotely sensed chlorophyll a rasters for several days and I need to get an average of the days represented as one raster layer. I've got QGIS 18.0 with the ...
1
vote
1answer
118 views

How to recode bands in which max value occur using ArcGIS Desktop?

I have 2 raster images; ras1 (an image with max value) and ras2 (an image with 5 bands). Basically. ras1 image extracted from ras2 images. I'd like to find bands from ras2 in which max value occur ...
5
votes
1answer
794 views

How to force RGB in a raster in QGIS?

I have rasters in 1 band 64bits float that represent real data values and for which I can set min and max using the stretch to min and max option in QGIS. I would like to convert these rasters to RGB ...
5
votes
1answer
458 views

Simplifying polygons made from binary rasters using ArcGIS Spatial Analyst?

I'm using MaxEnt to produce a species presence / absence raster layer. It works fine but I have to choose a cut off point for what constitutes presence or absence. As a result I end up with a lot of ...
2
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0answers
60 views

How to change the order of a raster in order to create mosaic with MosaicPro (Erdas 9.2)?

Is there a way to reorder the input files so I can control which ones are on top of the others?
3
votes
1answer
1k views

How to Calculate Utilization Distribution Overlap Index (UDOI) in ArcGIS Desktop?

I was wondering if any of you happen to have any information on how to calculate the Utilization Distribution Overlap Index (UDOI) in ArcGIS 10? If I understand it correctly the UDOI takes two kernel ...
2
votes
1answer
610 views

MOD 35 Cloud Mask HDF in ENVI

I am having difficulty getting ERDAS or ENVI to correctly read and display cloud mask attributes from MOD 35 HDF files. They files are displayed as 0-255, whereas I expected some kind of code 0, 1, ...
3
votes
3answers
2k views

How to remove empty classes from legend in ArcGIS Desktop?

I have a classification image with only 12 classes. I'm preparing layout using this image. when I add legend into layout page, a lot of empty classes loaded together with these 12 classes. Totally 255 ...
5
votes
1answer
933 views

How to load raster data with hyperlink path in ArcGIS MXD?

I have a problem/question and hopefully someone of you is able to help me: I have thousands of georeferenced raster files which have corresponding polygons (outer borders of rasters) with a hyperlink ...
5
votes
1answer
191 views

Calc bottomline of valleys

Which way do I calculate bottomlines of valleys or even more preceise: which way do I "find" valleys (for example suggested tectonic faults). Sample below shows a height profile (profile from line) ...
6
votes
1answer
643 views

Calculating “relative slope” per Mora-Vahrson method in ArcGIS

I'm a longtime lurker who finally decided to register on the forum (in no way driven by my need to have a certain question answered, of course...). I was contacted by a colleague asking for help ...
6
votes
1answer
272 views

Raster aggregation in ArcGIS Desktop?

I'd like to aggregate a raster from 1m to 6m in ArcGIS with a custom rule. For example, each cell value of aggregated raster = mean value of 5 highest cell values from 36 aggregated values. How do ...
2
votes
0answers
248 views

how to align vector and raster images? [closed]

How to align vector and raster images? For example vector images will be static/rigid and raster image will be morphable. For example I manually do initial guess and algorithm must converge to optimal ...
6
votes
1answer
1k views

Python equivalent of gdalbuildvrt

Is there a way to perform the same task as the gdalbuildvrt utility using GDAL Python bindings? So far I have not found any way to do this other than creating a vrt of a single dataset and manually ...
2
votes
1answer
122 views

d.rast.edit error when attempting to edit a raster

I always get an error when I try to edit cell values in a raster with the GrassGIS command „d.rast.edit“. The error under Windows XP/GrassGIS 6.4.3 says: Exception in thread Thread-29: Traceback ...
2
votes
1answer
283 views

Tiling Rasters based on an existing Polygon Shapefile (Vector Grid)

I have a tile index representing the tile scheme used to tile Lidar data. I want to tile imagery rasters using the same tiling scheme. I have not found anyway using open source tools to tile a ...
2
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0answers
85 views

What are the characteristics of a raster to Netcdf layer in ArcMap?

Specifically, when trying to edit the attribute table? This is would be for work purely in ArcMap, and converting raster to Netcdf. I have a land cover layer (that I've converted to a raster to ...
1
vote
2answers
515 views

SAGA-GIS Produces different results in command line than GUI

I have been working on a lidar processing workflow using SAGA-GIS. I determined my workflow on a single tile in the SAGA GUI and now I need to batch the operations on 100 more tiles. I wrote a batch ...
4
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1answer
283 views

How to create cohesive Spatial Pixels from Spatial Points Dataset

I have a Spatial Point DF spo (covering an irregular shaped area of interest). The data are not on a regular grid due to crs transformation. My goal is a raster with predefined resolution and extent ...
2
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1answer
669 views

How do I pass each parsed file name to the next tool in Model Builder? [duplicate]

I cannot get the Parse Path tool to pass each file name to the next tool. In the example shown, the Raster to Ascii tool will take the first entry in the 'filename' variable list as part of the output ...
10
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2answers
1k views

How can I improve my Georeferencing results?

Background This is my second question related to georeferencing naked raster maps in order to re-visualize them on different coordinate systems and in conjunction with other data layers. The previous ...
9
votes
4answers
2k views

How to “clean” and vectorize a raster map?

I'd like to make use of a geological map as shown in the example below, which is only a pretty small and downsized part of the map, so editing/redrawing doesn't seem to make sense in the end. My idea ...
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0answers
395 views

Raster Over Layer in Leaflet from GeoServer

I want to add a raster over layer onto the base layer and the raster layer is published by a Geoserver WMS. I set the raster layer's geographic coordinate system as the same as the cloudmate tiles. ...
3
votes
2answers
419 views

Determine density or cover from a raster layer that has been clipped by a polygon

I am a very new GIS user using ArcMap 10. I have a raster layer of tree canopy that I have clipped so that the layer is in a polygon that is a circle with a 2km radius. I have done this for four ...
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0answers
296 views

Raster satellite images for QGIS

When I try to apply a downloaded GIS satellite (t=rimage to Quantum, it doesn't seem to open properly. There must be a step-by step description on how this would be done effectively. Can anyone tell ...
3
votes
1answer
947 views

How to align two rasters of exact same cell size, extent in ArcGIS DEsktop?

I have two raster datasets. One is already georeferenced. The second one is not georeferenced but should have the exact same extent and cell size as the first one. It is supposed to exactly overlap ...
7
votes
2answers
2k views

How to sum pixel values within a polygon zone in QGIS?

I have two layers: a raster layer and a vector layer (polygon). I can see the values of the raster pixels but I don't know how to combine them with information from the polygon layer. More ...
1
vote
1answer
646 views

Trying to run raster calculator to build an expression for ls factor

I am trying to run a raster calculator, but it failed. I believe that ArcGIS 10 does not understand when I use the variable resolution. What do I need to put in its place? I took the equation from ...
5
votes
2answers
2k views

Exporting DEM-derived rasters to CSV from QGIS?

I have been able to import into QGIS a set of raster topographic maps and the associated DEM raster maps. It registered the two for me. From there I have calculated the associated slope raster map. ...
6
votes
3answers
5k views

How to make transparent the background of a topographic map in QGis 1.8.0?

I'm starting to use QGis 1.8.0. I have a raster topographic map, i.e. white background and black contour lines, houses, roads and so on. I want to make transparent the white background, so if I ...
0
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2answers
1k views

Exporting Grid from R to use it in ArcGIS

i want to export a grid from R into format readable by ArcGIS. how can i do so?
2
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1answer
263 views

Obtain normalized raster average per polygon?

I have a raster that contains percentages of total forest killed plus a polygon layer that defines different zones. My goal is to find a good statistical representative that describes the forest ...
3
votes
1answer
187 views

Creating a vector based design from a raster database

I have a raster table that I've created using Postgis raster. It has 365 records and the table looks like this: +-----+------------+---------+------------+ | rid | rast |filename |date_of data| ...
10
votes
3answers
1k views

How to speed up queries for raster databases?

I have a raster database in postgresql/postgis with these columns: (ID, rast, data_of_data). 'rast' is the column that has raster files in WKT format. An example query to find the DN value of a ...
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vote
0answers
250 views

Issues with building a VRT. from OS map tiles in QGIS

I am trying to speed up rendering of OS raster map tiles in QGIS. The tiles are 1:10k Tiffs - about 130 of them. When I attempt to build the VRT it says complete, then it shows up an error ...
4
votes
1answer
294 views

How to extract most probable flow line from multiple lines?

I have to apply uncertainty principle to computing flow accumulation using Monte Carlo method. I generate raster with random numbers which represents mistakes in creating DEM. Then I apply those ...
8
votes
3answers
2k views

GDAL and Python: How to get coordinates for all cells having a specific value?

I've got an Arc/Info Binary Grid---specifically, an ArcGIS flow accumulation raster---and I'd like to identify all cells having a specific value (or in a range of values). Ultimately, I'd like a ...
2
votes
0answers
695 views

why preview image is blank for ImageMosaicJDBC (postgis raster) layer?

I follow http://docs.geotools.org/latest/userguide/library/coverage/pgraster.html to publish a ImageMosaicJDBC layer in geoserver. the layer seems published ok and saved, but the preview of this layer ...
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0answers
89 views

blank preview image for ImageMosaicJDBC (postgis raster) layer [duplicate]

In geoserver, while publishing ImageMosaicJDBC layer seems no problem, the preview of this layer does not give me an meaningful overview image, only a blank image with the correct lat lon extend. Also ...
3
votes
2answers
482 views

How to export a raster into ascii without nodata values?

I need to export a grd raster file into ascii .xyz without nodata values. This is not a problem in itself...I´m using Saga-GIS export grid to xyz module.(ArcGIS 10.01 produces a very strange table of ...
11
votes
2answers
2k views

What to do with -3.4e+38 nodata values?

I am trying to process some bioclimatic raster files, such as can be downloaded from http://www.worldclim.org/current (bioclim set). They seem to have nodata values set to -3.4e+38 according to QGIS ...
2
votes
0answers
162 views

How to geocorrect in qgis?

I need to fit a utm wgs84 tiff raster to a topomap in the same projection. I use GCP and it invariably fails. The first raster uncorrected rater superimpose well, the "geocorrected" raster is ...
2
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0answers
77 views

Cubist Add-In for ArcMap

I'm looking for an ArcMap add-in that will create a raster based on rules from RuleQuest Research's Cubist .model files. Ideally, the add-in will give the user the option of matching input raster data ...