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

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644 views

Raster data array output flipped on x-axis using python/gdal?

I'm trying to create a raster using the python gdal libraries and I've gotten to the point where data is being output, but the output data is flipped on the origin point's x-axis. I know I must be ...
3
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1answer
112 views

1m cell size equivalent value in decimal degree

I'm doing re-sampling pixel size in ERDAS 2014,I'm using input image(Indian terrain) in GCS_WGS_84 projection. Now I have to keep out put cell size as 1m,what is the 1m equvivalent value in Decimal ...
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4answers
225 views

Convert line shapefile to raster, value=total length of lines within cell

I have a line shapefile representing a road network. I wish to rasterize this data, with the resulting values in the raster showing the total length of the lines that fall within the raster cell. The ...
3
votes
1answer
431 views

How to speed up band math in R 'raster' package?

I have some GeoTiff rasters with over 100 bands in total, but they are not huge: resolution is about 1200x600 and total size is less than 7 mb. I'm trying to do a simple NDVI calculation: raster ...
3
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3answers
2k views

How to Export Raster with same classification colors seen in ArcMap?

I have a single band raster, but i like to export it with the same colors as in Arcmap. Any help please.
3
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1answer
1k views

Conditional reclassification of a raster

I am attempting to do a conditional reclassification of an NLCD land-use raster. I specifically want to reclassify all developed areas (classifications 22,23,24) that are near a road (classification ...
2
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1answer
173 views

How to best remove rgb values outside of aerial image?

I have just converted RGB-TIF images to RGB-ECW for reasons of space and performance in ArcGIS. However, after the conversion, there are relics outside of the images which are not nodata values but ...
2
votes
2answers
314 views

SPOT NDVI time series

I have 423 spot.vgt ndvi from first April 1998 till 31 Dec 2009. I want to know how to stack these NDVI to have one image for time series analysis? Or better to ask how is it possible to analyze a ...
2
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2answers
936 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 ...
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2answers
2k views

PostGIS raster value of a lat/lon point

I have a tiff raster in my PostGIS 2.0 database. I want to get the value of the raster at a specified lat/lon point. I have: postgresql-9.1 postgis-2.0-svn with raster support a raster imported ...
9
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2answers
486 views

What is the correct way to convert a USGS Orthoimage from WorldImage format to tiled GeoTiff for GeoServer?

USGS provides different resolution orthoimage quadrangles in the WorldImage format (*.tif with an accompanying *.tfw world file). Some of these quadrangles can be used by GeoServer (2.1.0 - 2.1.2) by ...
8
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1answer
338 views

Where is this raster offset being introduced in the QGIS processing toolbox?

I'm using the (awesome!) processing toolbox in QGIS 2.0 to reclassify some NoData values in a raster from -9999 to 0, but at some point in the process there's an offset of about 0.2 degrees being ...
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3answers
1k views

calculate area of vegetations in a raster file

How do I calculate area of several vegetation types in a raster (.img file type) image. They are color coded. Am using QGIS (1.8.0) and ERDAS 9.2.
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votes
3answers
265 views

How do I display a raster “Background Value” as hollow for more than one set of RGB values?

I have two overlapping .ecw layers of the same area, though one is clipped in the middle, with a white edge. When I set the background value to 255,255,255, and define it as hollow, it only hollows ...
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3answers
6k views

How to add Raster legends in QGIS map composer?

Is there a plugin or method to add legends for raster layers (with a custom colourmap) as an item in the print composer?
7
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1answer
752 views

How can I change the class of one pixel in a 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 ...
6
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1answer
444 views

ModelBuilder: How to extract data by date, export to separate tables and interpolate tables to rasters

I've been using ArcGIS for a couple years, but when it comes to model builder I've only worked with very simple models. I'm hoping someone that is much smarter than myself can help me in building a ...
6
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1answer
2k views

Creating a mask with transparent pixels in python

I have a geotiff image with pixel intensities ranging between certain values. Lets say bewteen -2 and 2 (the image is normalized). I have a certain threshold which interests me, lets sat 1. I would ...
6
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3answers
3k views

Insert Raster to MXD using arcpy.mapping (ArcGIS 10)

What i want to do seems simple. But again i can't even find a workaround... I have got a lot of Raster-files (ESRI-GRID) which i need to insert into a layout mxd-file and then export the map to ...
5
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0answers
2k views

Loading raster from PostGIS DB into QGIS: succeeded yesterday, fails now [closed]

I have a PostgreSQL(v.9.2)/Postgis(v.2.0.3) database which includes raster layers (added through raster2pgsql). To open them in QGIS (v.1.8.0-Lisboa), the "Add Postgis layer" menu will not work; ...
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3answers
2k views

How to reclassify a float raster?

I have three rasters which represent distance (in metres) from certain things (bus stops, parks, libraries). I would like to reclassify these rasters so that they get integer values based on the ...
5
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1answer
1k views

Save Visible WMS layer to file

Is there tool to save currently visible WMS layer to file in QGIS, or some place in QGIS where you can get needed xml to fetch it using gdal ?
5
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3answers
354 views

Create Zonal Grid in R

Suppose I have a n*n raster, and I want to create k square blocks (k can be divided exactly by n*n ) for zonal analysis: for example, when n = 4 and k = 4 a 4*4 raster is create with value 1 1 2 2 ...
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2answers
1k views

How to enclose clustered points with polygon?

I have a raster with forest (1), no forest (2) data. "1" is represent single/few trees and there is gaps between them. I want to create a polygon around these trees to a forest map. It is not a dense ...
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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, ...
5
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1answer
2k views

Coordinates of upper left corner in the world file?

According to Wikipedia and ESRI last two lines in the world file represent x and y coordinates of center of upper left pixel. Now, if I have a world file like this: 32.0 0.0 0.0 -32.0 691200.0 ...
4
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3answers
517 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 ...
4
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5answers
238 views

How to group individual groups of pixels into a single class

I have a raster image with certain pixel groups of equal area. Each group represents a single house. I want all the pixels near a group of houses to have the same pixel value, i.e., I want to name ...
4
votes
2answers
321 views

Converting shapefile to raster: Character attributes

I've got a shapefile that I would like to convert into a raster, but the trick is that the attribute I want a raster version of is character data. I'm familiar with geoprocessing using GDAL (in the ...
4
votes
1answer
665 views

How to extract pixel value counts from a raster in QGIS?

How does one go about obtaining a summary of the counts of cell values within a raster in QGIS? I know QGIS is doing this, in order to provide the summary statistics and histogram in the properties of ...
4
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1answer
44k views

What is the difference between Vector and Raster data models? [duplicate]

From: http://support.esri.com/en/knowledgebase/GISDictionary/term/vector%20data%20model vector data model: [data models] A representation of the world using points, lines, and polygons. Vector ...
4
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1answer
243 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 ...
4
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2answers
1k views

How to get an extent for Raster using python

I have to get an extent of a given raster so that I can save it and use the same to clip another raster with that extracted extent. As of now I am stuck in the extent part. import arcpy from arcpy ...
4
votes
2answers
791 views

Spatial query of raster data

I have population distribution data as a raster layer and exposure contours as vector (polygon) layers. What I'd like to do is use the vector layer to estimate the population indicated from the raster ...
4
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2answers
369 views

QGIS Two Raster Data Sets with black line between the two sets where they join?

Where the two Digital Raster Quad sets (topo maps 7.5 Quad) overlap there is a significant thick black line (not a single line but wide and is wider the further south you go on the map). I am looking ...
4
votes
3answers
1k views

How to speed up Postgis raster layer display in QGIS?

i've been importing some digital orthophoto geotif files into postgis 2.0.1 via raster2pgsql tool (i also made 3 levels of an overview table - pyramid). Then i tried to import the layer into qgis via ...
4
votes
1answer
473 views

Generate centroids for vector polygons based on raster and land-use data using QGIS

Although QGIS has the ability to generate centroids for polygons, I am not sure how to generate centroids based on land-use development using raster data. Here's an example of what I'm trying to do: ...
4
votes
3answers
2k views

Export georeferenced image overlay from KML?

How might one export image(s) from image overlays in a KML file to a standard geo-referenced raster format like geotiff? Use case: NASA's Earth Observatory has a time series of the changing Athabasca ...
3
votes
3answers
189 views

How can I determine which raster attribute covers the highest area of a polygon?

I'm relatively new to GIS and QGIS but I have a problem that I'm not certain how to solve. I searched here for relevant information but found none. (Or, I used incorrect search terms.) My problem ...
3
votes
3answers
345 views

Scatterplot, correlation of dependence and r-square between two rasters

I have two rasters of the same region and of same resolution and I want to plot in a scatter plot their values and compute the best - fit line with r-square. Any idea how can I do this on Arcmap or ...
3
votes
1answer
542 views

Mapnik + OpenStreetMap + Shapefile with Raster Images + Mod Tile + PostGIS

I am new to GIS. I have a Shapefile (.shp, .shx and .pbf). The .pbf file contains path to PNG files located on my machine only. I was able to save the Shp data to PostGis via Shape2Gis tool. Now ...
3
votes
3answers
375 views

Where to obtain free 15m ASTER image for New Mexico?

I am looking for a free Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image that will let me to perform NDVI for the pilot crop health/soil moisture that can go as far back ...
3
votes
1answer
607 views

Why is Orthorectify button not active in Image Analysis Windows in ArcGIS10?

I wanted to Ortho rectify GeoEye HR imagery using existing RPC and IFSAR DTM in Image Analysis. According to ArcGIS Resource center ...
3
votes
2answers
446 views

Need to clip raster based on field name in ArcGIS 9.3

Is there a way around for me to batch clip a raster using a field name to create output a raster layer ? Much like using Split tool but it is for a vector. How about that for the raster side ? Going ...
3
votes
4answers
2k views

How to clip raster image by the extent of each row in a shapefile with ArcGIS 9.3

I'm using Python to clip a raster image by each row in a shapefile with ArcGIS 9.3. I am hoping to end up with one raster image for each polygon row, clipped to the extent of the polygon row. ...
2
votes
1answer
379 views

How to create a catchment from a point using a DTM raster in QGIS?

I need to find a better way to delineate a catchment from a given point on a watercourse using a DTM - currently I am either using FEH, or if the catchment is too small using contours to draw ...
2
votes
1answer
207 views

How to iterate GRASS region definition?

I am using GRASS r.skyview command (v.7, Windows) to determine "urban canyon effect" on pollution due to the presence of buildings. The command nicely works, unfortunately I need to process a very ...
2
votes
1answer
124 views

PostGIS Raster: Outputting raster into GDAL supported file?

I have import a raster into my postGIS database via raster2pgsql. My raster tiled to 100x100. Now I'm trying to export (output) the raster to GDAL supported file (for example: PNG). Following the ...
2
votes
1answer
331 views

Convert multiple Shapefiles in Raster in R(and then plot it)

I'm trying to convert several shapefiles in rasters at the same time. I already was able to read the shapefiles by doing this: library(maptools) shps <- dir(getwd(), "*.shp") for (shp in shps) ...
2
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1answer
2k views

Convert 32 bit image to 8 bit image in QGIS

I want to convert my images from 32 bits to 8 bits. I'm using otb to calculate texture and the raster output is on 8 bits, I'm going to use this information as a layer stack for my multispectral image ...