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

learn more… | top users | synonyms (1)

13
votes
2answers
2k views

How to smooth/interpolate a raster in python using GDAL?

This is my first post so please feel free to critique where necessary. Background: I am developing in Python and using GDAL from OSGEO to manipulate and interact with rasters and shapefiles. ...
11
votes
1answer
1k views

Random sampling of raster using R

Is there a straightforward way of randomly sampling a raster so that the output of the process is a raster? I'm using an example that I found on the r-sig-geo list and I have also tried the ...
7
votes
1answer
5k views

Converting a polygon into a raster using R

I'm trying to convert a shapefile into a raster within R. My approach is to read in the raster as follows: library(rgdal) # Loads SP package by default demo <- readOGR('F:/data/', 'shapefile') # ...
16
votes
2answers
2k views

What resampling technique should be used when projecting aerial photos?

I'm doing some time-intensive projecting of aerial photos, and I'm curious - what resampling technique is best to use on aerial photos? In ArcMap, my options are NEAREST, BILINEAR, CUBIC, and ...
11
votes
1answer
4k views

Differences between Raster Dataset, Raster Catalog, and Raster Mosaic

I have about 40 scanned, colorful Geology maps that are GeoTiffs. I want to bring them into an Esri FileGeodatabase to lower their size, combine them as one and display them with a mostly transparent ...
11
votes
1answer
721 views

Method to shade or overlay a raster map to reflect time of day and ambient light

I have a daytime raster of my study area. I have 20+ counters in the study area that count "stuff" with a timestamp. Using PyEphem I determined the type of ambient light for each collected data ...
10
votes
2answers
800 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 ...
10
votes
2answers
11k views

How can I join several raster files using QGIS?

I'm new to QGIS. How can I combine multiple raster layers into one layer? The raster images are of different areas with very little overlap. The goal is to bring numerous town plats into one project. ...
7
votes
6answers
5k views

Rasterfile clipping error: Cannot compute bounding box of cutline

I have a raster file and want to clip it, a vector file is supposed to be the mask layer. I use the most obvious method (Raster->Extraction->Clipper). No matter what I do, I get this error (see pic): ...
6
votes
2answers
2k views

How to extract values from rasters at location of points in R?

My question is about extracting values from rasters at the location of points. With the function extract this is very easy, and the function gives me a dataframe with the values of all the variables ...
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 ...
6
votes
1answer
4k views

How to import a raster into PostGIS?

I'm trying to follow the instructions here to load a raster into a PostGIS database: python raster2pgsql.py -s 4269 -I -r *.tif -F myschema.demelevation -o elev.sql I understand that I replace * ...
6
votes
2answers
1k views

Creating shapefile of satellite image footprints?

I'm looking for a tool or a workflow to compute satellite image footprints, for a large number of images across directories, and produce a shapefile. Ideal work flow would be: fire up tool point to ...
13
votes
5answers
2k views

Is Hillshade option in ArcMap rubbish or is it me?

Here is a pretty pic of the raster I am using - with no effects applied - just the color ramp and historgram adjusted to show out all the relief - all be it in a very 2D way! I have a raster layer ...
8
votes
5answers
943 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 ...
8
votes
2answers
2k 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 ...
6
votes
3answers
5k views

Finding nearest raster cell value based on vector point?

I have two layers in ArcGIS: One is a vector point and the other is a raster layer. I want to append the value of the raster data grid to the vector point. The problem is the vector point is away from ...
5
votes
1answer
647 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 ...
5
votes
1answer
321 views

Unknown Coordinate System on old drawing

I work with many old civil engineering documents, and occasionally I'll need to georeference one which has coordinates pairs listed at many given points but does not list which coordinate system these ...
4
votes
1answer
940 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 ...
4
votes
1answer
998 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 ...
4
votes
1answer
2k views

Loading a raster using QGIS into a PostGIS2.0 enabled database

Following on from my attempt to install a postgresql 9.1 db with postgis 2.0 on windows 7, I am trying to figure out how to load a raster. I have successfully loaded a shapefile, and am trying to do ...
8
votes
1answer
2k views

GDAL RasterizeLayer Doesn't Burn All Polygons to Raster

I am trying to burn a shapefile to a raster using GDAL's RasterizeLayer. I pre-create an area of interest raster from a different shapefile, given a specific pixel size. This AOI then serves as a base ...
7
votes
4answers
3k views

How to install “1-band color raster color table”?

I would like to use the "1-band raster colour table" extension. I'm using QGIS Wroclaw 1.7.4. In the plugin installer I can't find this extension, even I quote for third party extensions thing. Does ...
6
votes
1answer
232 views

How to create points around edge of viewshed results?

Is there a tool or module, or multiple tools, in ArcGIS that will allow you to automate the creation of points around the outer edges of a viewshed? What I am trying to do is gather data about the ...
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 ...
6
votes
4answers
1k 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 ...
6
votes
3answers
5k views

Clipping a raster using a polyline or polygon

I have a large raster created from values that cover the whole United States and Alaska which are both polygon and polyline features, this raster was caluclated using Spatial Analyst IDW ...
5
votes
3answers
611 views

Finding outliers with wrong Z values in LIDAR data

I have more than 2000 XYZ (only ground points) .txt files and I have to do Quality Control (QC). Let's say I have file, which I converted to multipoint (or even singlepart feature). I have mean Z ...
5
votes
3answers
3k views

Creating a raster surface of overlaps from vector polygon shapefiles?

Basically what I'm trying to do (in ArcGIS 10) is to compare three vector files in order to create a 'comparison' raster layer. I tried using Data Comparison (under Data Management tools) but it ...
4
votes
1answer
209 views

Create a point at the highest value in a raster ArcGIS 10.1

I am trying to find the location of the highest value pixel in my Direct Solar Radiation Raster. I can see the extent of the data in my raster but don't know where the highest value pertains to. Is ...
4
votes
3answers
602 views

Loading raster data to postgis

I'm a newbie in GIS technology and need some help in loading a rainfall radar raster data into PostGIS. The raster image is shown here: What I need is to store in the database the radar ...
4
votes
1answer
2k views

In ArcGIS 9.3, how do I split a 3-band raster (.tiff) file and summarize the band values?

Using ArcGIS 9.3, I would like to make a new, single-band raster file that includes only one value: a summary of the three existing bands. The composite band is currently a composite .tiff file. ...
4
votes
2answers
1k views

Calculating Net Primary Production (NPP)?

When I calculate Net primary production (NPP) for a local scale, what kind of software should I use? I always use ENVI, ERDAS IMAGINE, ArcGIS for Desktop and IDRISI. Is it possible to use these ...
3
votes
2answers
267 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 ...
3
votes
1answer
496 views

How does cost allocation work?

Why, when I use the cost allocation function of Spatial Analyst, is space not allocated in all input source locations (as shown in image below)? In particular, the input raster has 18 spots while the ...
2
votes
2answers
101 views

Reclassify rasters using GDAL and Python

Using @SS_Rebelious very useful answer, I am trying to reclassify rasters using GDAL and Python. I have a grayscale raster (with values ranging from 0 to 255) and I want to reclassify it to a binary ...
2
votes
4answers
139 views

Measuring area of raster classes?

Are there any tools or methods in ArcMap that can measure the area of each level of the kernel density output? Note this is just a kernel density plot (not a shape file or polygon). Kernel Density ...
2
votes
1answer
282 views

How can I dynamically trim the informational border off of FAA sectional raster charts?

I'm trying to write a script that can automatically use GDAL to crop the informational border from the FAA's published sectional charts (GeoTIFF) found here: I know that I can use gdal_translate ...
2
votes
2answers
3k views

How to convert .geotiff --> .tiff?

How to convert .geotiff files to .tiff files (ordinary plain images)? Basically, I have cropped the image to a rectangle of interest and knowing its left-lower location and having chosen the pixel ...
2
votes
1answer
1k views

Raster Version of Spatial Join (one to many) [duplicate]

I have two raster layers that are identical in shape (they overlap exactly) and I need to perform the raster equivalent of a Spatial Join (one to many). My files need to stay in raster format ...
2
votes
1answer
302 views

Raster as Attribute Field Error

I'm using Arc 10.1. I am creating a parcel inventory where I would like to have a photo of the property attached as an attribute and view-able with an HTML popup. I have a polygon feature class built ...
2
votes
2answers
715 views

Conditional combining of multiple rasters to produce one output using Python?

I have two rasters for same spatial extent and need to compare both rasters cell by cell and produce one output raster. Each has 10 land cover classes. Based on those 10 classes the comparison should ...
1
vote
3answers
8k views

How to calculate Raster Area per Polygon?

In ArcMap, I have a raster file that contains 6 classes of landcover and a shapefile that is the census data (OA boundaries and their population). I want the area of each class in each OA? For ...
7
votes
1answer
184 views

Finding largest number of observations within a given radius

I have the following problem: Given the location of insured properties (say houses with fire insurance), i have to find the largest sum of insured values which fit into a 300m radius. Now, my first ...
6
votes
2answers
2k views

How to change null values raster values to 0 in QGIS?

I need help... I'm having problems with QGIS. I have some rasters that appear to have null values, even though I reclassified them to obtain a boolean raster :( How can I change the NULL values to 0?
6
votes
3answers
1k views

How do I extract a raster's extent in python?

I am looking for an easy way to extract a raster's extent in python. Currently, I am using gdalinfo and then parsing out the corner coordinates. The problem with this approach is that gdalinfo is ...
6
votes
1answer
1k views

Counting NoData values in raster using ArcGIS Desktop?

I have created a raster in ArcGIS Desktop 10 with a large number of holes (NoData) in it. I want to fill the holes using something like the the following: rOut = ...
5
votes
1answer
477 views

Creating field with specified slope projecting from 3D polygon?

I am trying to figure out how to create a elevation raster from a known location (3D polygon) that projects at a specified slope (1%) for a specified distance(1-2 km). Does anyone have any idea how ...
5
votes
2answers
4k views

Convert x, y position in georeferenced image (with world file) to longitude, latitude?

What steps do I need to do in order to calculate longitude and latitude for a specific pixel in a georeferenced image? For example this image ...