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

learn more… | top users | synonyms

2
votes
1answer
3k views

Converting Raster Data to Polygon data

I am trying to convert a raster data to polygon data. Previously I was using the shapefile.py to create point data on individual lat/lon on the raster. But that will create a Huge data and querying it ...
6
votes
3answers
3k views

Raster: How to get elevation at lat/long using python?

I was wondering if anyone has some experience in getting elevation data from a raster without using ArcGIS, but rather get the information as a python list or dict? I get my XY data as a list of ...
7
votes
2answers
883 views

What Open Source (command line/API) method is there to orthorectify and georeference an aerial image given telemetry data?

How can I take an image and orthorectify it automatically with open source software? The information associated with each image is: camera specs latitude, longitude, elevation of the camera ...
10
votes
3answers
3k views

How can I mosaic images in ArcMap without it affecting the colour?

This is 4 images (NE, SE, NW, SW) sections of imagery. They have some overlap between them. Working with 1m 3-band orthoimagery. Different parts are sometime flown at different times/sources hence ...
3
votes
2answers
62 views

Where to look for oceanographical/environmental data for the Arctic (Baffin Bay/Davis Strait area)

I am looking for oceanographical/environmental variables that are available for Baffin Bay/Davis Strait area over the time period of 1995-2011, however, I am not familiar with ...
7
votes
1answer
132 views

How to improve the display of color images?

I've found some really nice color ramps for portraying rasters, but in ArcGIS and QGIS, they don't seem to be easily usable for a finished product because their complexity causes obvious steps rather ...
2
votes
1answer
496 views

Creating a constant elevation raster with multiple attributes

Is it possible to create a raster with a constant value with multiple attributes? Such as: rowid value count Name 1 630 36000 Forest 2 630 75000 Anthro 3 630 2600 ...
6
votes
2answers
1k views

Creating a multispectral image from scratch

I want to make a multispectral image from cero to do some tests on it. Something really simple like 5 completely uniform bands with salt and pepper noise on them or a square of different values at the ...
3
votes
1answer
155 views

Assigning Probability to cells

I am working with the image below and I am trying to find how many pixels are in the grey corners of the image, and I want to assign them a probability of 5%. The bottom layer is my DEM and the top ...
3
votes
1answer
363 views

Vector to Raster for Smoothing purposes

I have a vector file that represents transit scores by CT of a city. It shows harsh boundaries where one CT has great access to transit and right beside that CT is one that has extremely poor access. ...
5
votes
2answers
468 views

Optimum grid/pixel size for interpolating rainfall and temperature

I have a set monthly rainfall and temperature data within an approximately 100 x 100 km study area. The sampling points are unevenly distributed within the study area. Based on a paper by Janis et. ...
3
votes
1answer
452 views

Creating a Raster Filter

I am looking to create a raster filter which reclassifies single or contiguous pixels less than, for example, 30 pixels (shown in white below) into another class (shown in black). The filter, ...
3
votes
1answer
350 views

Why does QGIS Polygonize ignore the no data value?

I'm running into an issue georeferencing a number of PNG image files. The files simply contain an image where each pixel is either transparent or a single color, forming a coverage mask. In the past, ...
9
votes
3answers
4k views

Best method to aggregate 1m DEM mosaic to 10m DEM

I have a mosaic of a 1m LiDar derived DEM. I need to output a subset of the data as a 10m DEM. I am currently using the aggregate tool in ARCGIS 10 to produce a mean value for each new 10m pixel. ...
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
983 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
730 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
432 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
777 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
187 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
728 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
109 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
198 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
945 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
668 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
263 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
305 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
207 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
320 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
914 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
462 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
696 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
240 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 ...
17
votes
3answers
761 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
883 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
82 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 ...