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

learn more… | top users | synonyms

4
votes
3answers
1k views

Convert an arbitrary meta-data-free map image into QGIS project

My background: experienced programmer, amateur historian, complete beginner to GIS (so I'm using QGIS). I did learn to use the QGIS georeferencer tool though. The input: suppose I have an image like ...
5
votes
1answer
1k views

Raster data on PostGIS

I need to publish raster and vector data through GeoServer WMS service and I have already chosen PostGIS as datasource to keep vector data. Now I would like to know what is the best practice to work ...
5
votes
1answer
749 views

Raster processing with Python or Arc raster calculator

I have 4-band NAIP imagery that require the following processing steps: Convert to 8 bit unsigned B/W Reverse (note not inverse) the image, so that dark values appear light and light values appear ...
3
votes
2answers
1k views

Image does not display after clipping raster

I am using ArcGIS 10. I am trying to clip an NLCD layer from a vector polygon. I have used the Clip Raster tool in Data Management and Extract by Mask tool in Spatial Analyst among other things. My ...
3
votes
1answer
292 views

how can I obtain the areas where my rasters overlap, using Qgis?

I have a bunch of raster files showing the distribution of different species of mammals, and I would like to obtain the areas where they overlap, the areas in whitch more than one species can be found ...
2
votes
1answer
438 views

How to add EPSG:5235 to QGIS?

First of all I should say I am new to EPSG and QGIS world.Then I want to Georeferced Raster image to EPSG:5235 in QGIS. But in Qgis I can't found above EPSG. How I add this EPSG to Qgis ? Pls help ...
2
votes
1answer
791 views

Loading Raster and vector data In MapGuide using Maestro

I am new to Mapguide , working on it for my summer Internship.I have Installed it perfectly. Now the task is to load vector data and Raster data in map Guide (mainly have to load *.shp files and *.tif ...
3
votes
1answer
188 views

storing jpeg in spatialite database

How to store jpeg file in spatialite blob column so that spatialite gui and Qgis can recognise the format and show the image. I have created in memory jpeg from raster bands using jpeglib and stored ...
3
votes
2answers
753 views

How can I apply stretch in ArcGIS 10 Image Analysis Window?

I need to apply stretch to ArcGIS 10.1 exported raster. The best way to accomplish this task: Image Analysis Window, because there are fine tools to equalize raster data. 1 - This is my IRS-P6 24m ...
5
votes
3answers
110 views

Please help me identify this CRS. How could I identify this myself in the future?

I'm trying to georeference this map, but I don't recognise the CRS. It is for a region of Tanzania. Here is the image on imgur in case Stack Exchange compresses the image. How would I go about ...
2
votes
1answer
2k views

Publish PostGIS raster to geoserver

I have a database of raster and vector and I want to use them in my webmapping. There is not a problem to publish the vector using geoserver but I can't publish my raster. Is there possibility to ...
6
votes
3answers
4k views

Raster mosaic not displaying raster values ArcGIS 10

I have eight DEM tiles that I downloaded from the USGS National Elevation Dataset. The individual rasters are displaying correctly, but when I try to combine them in a Raster Mosaic I get arbitrary ...
2
votes
2answers
203 views

Go from multiple rasters to R compatible table

I have a set of geocoded, pixel-aligned rasters which I would like to use in a model in R. I would like to produce a table of data that can be imported to R, in which there are as many columns as ...
0
votes
0answers
21 views

Storing Image data to spatialite [duplicate]

Possible Duplicate: spatialite storing raster data I want to store geotiff data to spatialite databse. I am using gdal to read metadata and reading tiles convering them to hexwkb format and ...
7
votes
3answers
972 views

Creating raster or vector raster from DEM point file?

i have a point shape of 75.000 elevation points in a regular 5 m grid. We now want to create a polygon grid with the elevation points as "centroids". Unfortunately, all attempts to do so fail: I ...
4
votes
1answer
89 views

Rasterise heights from a 3D linestring

I have a 3D network of streams represented using linestrings with Z-coordinates. I would like to rasterise this feature, where the raster values represent the linearly interpolated Z-values between 3D ...
1
vote
2answers
1k views

QGis problem with raster transparent

I am new to QGIS. I found the problem impossible to solve the parts of raster data that are in TIFF format should be made transparent. What do I do?
12
votes
4answers
674 views

Dikes extraction from DEM

I do have DEM of 1x1 meter and original LiDAR point cloud in .las, that DEM is made of. I need to extract river dikes (highest points of the dikes) to vector feature (point, polyline). Any idea for ...
1
vote
1answer
273 views

Adding Field to Raster

Good day! I have a shapefile which contains X-specific field. I want to add this X-specific field (integer) to a raster dataset. I am using ArcGIS 10. How can I do this? Thanks.
4
votes
1answer
1k views

How to store raster data in spatialite?

I want to cache my raster data(large geotiff files) on local database. I thought to use spatialite. I found librasterlite which provide functionality to do that. Can anybody point to some tutorial on ...
6
votes
2answers
312 views

Wavelet vs Discrete compression for imagery

What is the main reasons to choose wavelet (jp2, sid, ecw) instead of discrete (JPEG) compression methods for raster data? Lets limit this question to aerial imagery and lossy compression. Why ...
3
votes
1answer
215 views

how to square the pixels of a GeoTiff

I have a GeoTiff that has been supplied to me with non square pixels (I suspect due to reprojection to lat lon at some point). However the next step in my processing chain requires a Arc ASCII grid as ...
1
vote
1answer
117 views

Can I avoid runtime raster interpolation by creating an image pyramid to match the zoom scales?

For image quality and performance reasons, it would be best to perform interpolation of my large TIFF image of the world (10GB) beforehand to all the zoom scales I need to display at so that MapGuide ...
1
vote
2answers
322 views

How to implement a spatial query on polygon data for a specific point?

I have vector data fed into a database which returns a report at province level upon querying. This is implemented in a web tool. I want to add an extra functionality at point level, where I can ...
8
votes
2answers
941 views

Resample binary raster to give *proportion* within new cell window

I would like to go from a binary raster of forest/non-forest at 30m resolution to a raster at 240m resolution with the value of each cell being the proportion of that cell forested - i.e. the data ...
6
votes
4answers
2k views

How to sum up pixel values in QGIS?

I need to know the value of the sum of all pixels in a raster. However, in the Statistics section of the Metadata tab in Properties, under Sum of All Cells it always indicates 0.00. I have tried with ...
4
votes
1answer
482 views

Trouble Tabulate Area

I am using Kansas Cropland raster data from NASS with tabulate area to find out acreage of different crop types. The python I used works fine for 2006-2009 (56 meter cell size), except 2010 & ...
4
votes
3answers
2k views

How can I specify the CRS of a raster layer in pyqgis?

I manipulating netcdf raster data from the QGIS python console. The metadata of my netcdf file does not provide the Reference system. However I know it is 'EPSG:4326' I am writing a python script to ...
4
votes
4answers
709 views

How to sample raster datasets at ALL points?

I know it is possible to use tools like ArcGis's 'extract sample' tool to extract values at a given number of points. I would like to sample every pixel in a raster, and drill down through all other ...
4
votes
1answer
249 views

Reclass all values < 0 to -9999 in PostGIS

I have a tiled raster in a PostGIS table and I would like to change the value of all pixels which have values less than 0 to -9999. How should I do this? I suspect it involves ST_SetValue and ...
18
votes
3answers
782 views

How to count consecutive pixel values for a set of rasters?

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 ...
6
votes
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
votes
3answers
4k views

ArcGIS Export Selected Raster Graphics

I'm having a problem exporting raster graphics using ArcGIS 10. It seems simple enough, but for some reason I cannot get ArcMap to work with me. Here are my steps: Add a raster to ArcMap Open the ...
2
votes
1answer
914 views

Filtering a raster by pixel value ? (Qgis)

I have downloaded Globcover data in GeoTIFF format. I want to create a new grid which only has values where the Globcover data (the only band in the TIF file) has one certain value (==190). Can I do ...
20
votes
3answers
2k views

Packing Polygons within polygon

I have a Boolean raster. In the grey areas of the raster I would like to fit a given size polygon within a contiguous extent. Basically, I have an irregular polygon, and i would like to "fit" a ...
1
vote
0answers
84 views

Make a thumbnail of a raster in PostGIS

I'm fiddling around trying to create a thumbnail of a fairly large (originally 27MB) raster, chunked into 64x64 blocks. I've got the following and it works, quite well, but I'm wondering if there is a ...
11
votes
1answer
574 views

QGis raster terrain analysis - The curvature filter puzzles me

I am a french Master student at university Grenoble INP, and during my master project I have worked on DEM (raster) terrain analysis. Thus, I have read the source code of several QGis-1.7.4 raster ...
2
votes
1answer
5k views

Convert a Tif raster file to vector shp file in QGIS

So I've been trying to convert a georeferenced Tif raster file into a vector shp file using QGIS. It's seems to complete this but it ends up giving me a feature class that has over 500,000 features, ...
3
votes
0answers
265 views

GFS SIG/SFC file format of siganl.gdas/sfcanl.gdas analyzing/decoding problem

I am creating a database from datafiles. I encountered many fails and errors, which I have already fixed (also with the help of this Q&A web). Now I am stucked a bit in decoding of 6 files because ...
2
votes
1answer
330 views

How to change the raster NoData value with ArcObjects?

I am trying to change the a raster's NoData value with ArcObjects and keep coming up short. Here is the code that I thought would work: IRasterDataset _dataset = ...get the dataset... object[] ...
5
votes
1answer
394 views

Mosaicing indexed colour rasters with independent colour tables

I have a large number of single band rasters that are colour indexed TIF files. I want to mosaic them using GDAL (or similar non-proprietary software with a Python API I can call as part of a bigger ...
3
votes
1answer
2k views

ArcGIS 10 trouble displaying raster correctly

I think I've come across a Bug in ArcMap 10 in displaying rasters. This particular model comes from the USGS GAP Species dataset with metadata hosted here. I'd like to know if anyone else has ...
3
votes
1answer
317 views

gdalinfo gives no georeferencing information for a PostGIS raster

I have a PostGIS raster dataset which I am trying to access via GDAL. I've had various problems with making this work, so thought I'd try running the gdalinfo command to check that GDAL can actually ...
3
votes
1answer
597 views

PostGIS 2.0 ST_Transform with Rasters cannot find custom SRID

I'm trying to calculate an average value in a buffer around a point. Given a raster in EPSG 4326 and a similar point, this is fine, except that the values will be skewed as they are not projected in ...
14
votes
8answers
9k views

How do I create a shapefile showing footprints of Rasters?

I have around 1,000 satellite images in tiff format, and I want to create a shapefile which will serve as an index to the rasters. This is something similar to a raster catalog, but I do not want to ...
1
vote
1answer
358 views

How to serve raster mosaic to AutoCad Map 3D?

We are looking for a way to serve all the raster datasets we've collected over the years as a mosaic we have built in ArcGIS so that the AutoCAD department can simply import the mosaic and it will ...
2
votes
1answer
403 views

How to overlay my interpolation within the boundaries of Quebec?

I am trying to create interpolated maps within geographical borders. I have the coordinates and values to the points I am trying to interpolate. I also have a map of the geographical land mass in ...
4
votes
1answer
474 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: ...
0
votes
4answers
3k views

OpenLayers (allOverlays): Vector layer not rendered without raster layer beneath it

This is another newbie question. I'm trying to create a map using OpenLayers that comprises only of vector layers from a WFS server. However, I'm thwarted because my vector layer won't render unless ...
2
votes
1answer
435 views

Recreating A Lat/Long Grid Using a Specified Formula

I'm trying to recreate the Gridded Mercury emissions 2000 (0.5 x 0.5 degree grid) designed by the Arctic Monitoring and Assessment Programme. The file is in ASCII format, but without any coordinates. ...