Questions tagged [raster]

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

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14
votes
4answers
4k views

Removing band from raster in QGIS

When I process a raster in QGIS it creates a second band. It appears that the band has no useful data. I like to use the Raster Colours Tool and it will not accept a raster with anything more than one ...
11
votes
2answers
691 views

How sensitive is Landsat to atmospheric correction?

How important is it to correct Landsat for atmosphere, haze and convert DN to reflectance? What impact does it have on the results, say for many of the vegetation indices?
3
votes
2answers
2k views

Change output file type in QGIS georeferencer?

I have successfully georeferenced a raster file via the Georeferencer plugin (Georeferencer GDAL Version 3.1.9) in QGIS 1.7.0. However, I noticed that the output georeferenced raster file is in TIFF ...
9
votes
2answers
4k views

Modify raster layer display and symbology properties programmatically with arcpy or ArcObjects

I have over 1500 NITF files that I need to be able to modify the layer display and symbology of programmatically from within ArcMap. I need to set the properties outlined in red below: I've looked ...
2
votes
1answer
1k views

GeoTIFF raster layer, c#

We have a map rendering engine (renders from MapInfo Interchange Format). This engine uses Mercator Projection. Now we have to insert a raster layer (orthophotos of a city), we have GeoTIFF files with ...
3
votes
1answer
572 views

Taudem Resources

As I frequently deal with hydrology, I've heard Taudem mentioned quite a few times. I'm finding all sorts of information, but much of it is dated for use with previous versions. In addition, the ...
7
votes
2answers
3k views

How can I calculate the vertical distance to the nearest water?

Summary: I would like to create a raster where each cell contains the vertical distance to the nearest water (a decent approximation would be acceptable). The problem is that I'm not sure how to go ...
4
votes
3answers
874 views

Overlay polygons on raster colour map to extract area values for each colour within each polygon

Does anyone know an answer to the following: I have a set of polygons created as the MCP of animal movements. I also have a habitat colour map raster, with 13 different habitat types as different ...
5
votes
6answers
9k views

Removing No Data From Raster (*.sid) using ArcGIS Desktop?

I have an Image.sid that has a white border which is No Data. I've tried using Clip Raster Tool with no success. I've also changed the symbology value for No Data to be transparent. I'd like to ...
8
votes
1answer
640 views

QGIS composer - How can I eliminate striping across transparent raster layers?

I have downloaded QGIS dev version 1.7.0-114 and I have come across some weird behaviour in the composer. I create a map with a hillshade and a transparent DEM ontop of it, pretty standard stuff. ...
6
votes
5answers
2k views

Clipping image with Basic (ArcView) level license of ArcGIS Desktop?

Is there a way to trim a geo-referenced air photo to an irregularly shaped boundary? I tried the clip tool shown in my attachment, but it didn't work. It looks as though the output extent field ...
2
votes
3answers
354 views

Trying to make private land white overlay hillshade?

I'd like to have anyone's feedback on this draft map I created. Tried to make the private ownership white but since it's RGB is not near to 255. I've seen someone created this map similiar to it and ...
1
vote
2answers
8k views

Removing overlap in raster using Erase command line?

I am trying to erase a raster and is there a erase command for the Raster side? I am using ArcGIS 9.3.1. I have 2 rasters that are in the Landcover and there is overlap in between and would like ...
7
votes
2answers
10k 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 http://www.shadedreliefarchive.com/...
7
votes
1answer
1k views

Is there a way to get the percentage of different landuse types upstream of a given point?

I'm a fairly novice GIS user and know just enough to get in trouble in a lot of cases. I am trying to look at the connection between several measured parameters at a few hundred stations along ...
1
vote
3answers
837 views

Point to raster Issues

I am creating a 3D subsoil model for display in ArcScene - I can get it displayed nicely as points but in order for the model to be easier to read I need it to be displayed as a raster. Every point in ...
3
votes
1answer
2k views

Cropping an image with a map extent

I have an raster file in my server space, which has the same projection as my webmap, and I would like to crop the image by passing the visible extent of a webmap. I think the cropping function is ...
1
vote
2answers
260 views

Setting Rasters to the exact same display

I have been tasked to make a series of .jpeg outputs of different sections of a dike displaying elevation data. My problem is that the data i have been given is GIGANTIC, almost the whole region made ...
0
votes
1answer
810 views

ArcGIS Desktop 10.0 -- layout Data Frame Grid color inversion on export or print when other rasters are active

Having a problem with ArcMap 10.0 SP1 Data Frame Grid of graticule inverting color on export or when printing. Occuring on multiple classroom PCs all working with the same datasets. Exporting to ...
4
votes
3answers
5k views

JPG file all black when added as raster in QGIS

I add a new raster layer in the latest QGIS and select a JPG file, but it is all black. I tried adding the TIF version of the same image and that worked. What is it with the JPG, and how should I ...
6
votes
2answers
773 views

Raster to Vector

I want to map out moisture availability using satellite image but I do not know how to convert the raster image to a thematic map with limiting boundaries like state boundaries. I am using ArcGIS 9.3 ...
2
votes
2answers
1k views

Using Flex to display single rasters from raster catalog in ArcSDE/ArcGIS server?

One of the front end develoeprs here is having issues displaying, or working out how to display a single raster held in a raster catalog in ArcSDE using the Flex 2.2 API the Raster Catalog holds ...
4
votes
3answers
2k views

Loading multiple raster files from list into ArcGIS Desktop?

How to select and load multiple rasters from one folder in Arc? My situation is probably familiar to some of you. I do have 3 folders with houndreds of maps in it. I do have also overview sheet, ...
7
votes
2answers
6k views

How do I calculate a weighted centroid with respect to a raster, e.g. population weighted centroid

In ArcGIS 10.0, how do I calculate the weighted centroid of a collection of polygons, where I want the weight to be a raster layer. In particular I am using a raster of population counts and would ...
6
votes
1answer
1k views

QGIS WKT Raster Plugin error, what does this mean?

I have been playing with the WKT Raster plugin. I have installed the WKT Raster experimental binaries in PostGIS successfully and followed the instructions in the read me to the letter. When i am in ...
1
vote
1answer
559 views

How to use r.patch with two maps having different colortables?

I am using r.patch to combine two raster maps in order to fill in the null values of the other. Is there a way to use r.patch but still maintaining the colortables of the separate raster maps? I do ...
5
votes
5answers
1k views

How to save a raster and vector into a single PNG file in GRASS?

I am trying to save a raster and vector into a PNG file. The vector is overlayed on top of the raster map. I was only able to save the raster file into a png using r.out.png but without the vector.
5
votes
2answers
2k views

How to return raster values based on polygon (shapefile) boundaries in QGIS?

How to return raster values based on polygon (shapefile) boundaries in QGIS? Is this an elementary question, because I am finding it hard....... Ideally I would like a neat workflow as I am likely to ...
6
votes
1answer
2k views

How to modify the colors of a raster map to use only one color in varying shades?

I have a raster map in GRASS containing elevation values. I want to display the elevation values in only one color (specificaly blue) but in varying shades of blue. I tried the options in r.colors, ...
2
votes
2answers
141 views

Where can I get an ocean shaded relief for Central America?

Does anyone know where I can get an ocean shaded relief for the Central American coast?
5
votes
1answer
1k views

affine transformation on geotiff

I have a bunch of geotiffs stored in a PostGIS DB that i am mounting on my OpenLayers map. They all have the geoTransform information in them. I just want to know how i can mount them on my ...
1
vote
0answers
678 views

16bit grayscale raster displays all black in Geoserver

I have a 16-bit raster (MrSID) that I want to display in Geoserver 2.0.2 but it is displaying as all black. If I create a new style similar to the default raster.sld but with graychannel element the ...
47
votes
7answers
142k views

What are Raster and Vector data in GIS and when to use?

What are raster and vector data in the GIS context? In general terms what applications, processes, or analysis are each suited for? (and not suited for!) Does anyone have some small, concise, ...
3
votes
1answer
591 views

Problem in r.resample

When I run r.resample to crop a map by using a vector and a mask, the resulting map has the same shape as the vector that I used but does not replicate (exactly) the portion of the raster map that I ...
4
votes
2answers
1k views

How to delete a base map in GRASS?

I'm trying to delete a map that I used as a mask before, but I cannot delete it using g.remove. It displays this: g.remove rast=raster_Mnorzagaray@PERMANENT [raster_Mnorzagaray@PERMANENT@PERMANENT] ...
6
votes
2answers
3k views

How to set the value of a pixel based on its current value?

I am attempting to set the value of a pixel based on its current value. I am using the Raster Calculator in Quantum GIS dev 1.7 trunk. For example, if the value is 0, I want to set it to 255. Based ...
7
votes
1answer
1k views

GRASS - Will r.to.vect work on this scanned map?

Total GRASS noob here. I have several very large hand contoured maps to digitize, and this thread intrigues me. In the past I have spent hours upon hours digitizing these maps and revisions in ArcMap. ...
3
votes
1answer
371 views

Two rasters created from the same polygon have different extents?

My problem is that I am trying to export some rasters to Rockworks so that I can create a sand layer from them. Rockworks requires the grid files i use to have the exact same XY co-ordinates. So i ...
3
votes
1answer
2k views

Count of raster cells as variable in ArcGIS ModelBuilder?

I want to use a cell count of an integer raster as a variable in Arcgis 10 ModelBuilder (and later in a python script), but can't seem to find how to access this information. Is there a (python) ...
1
vote
1answer
761 views

How to export a png file from a raster file? r.out.png has an error

I used r.out.png to export a png file, but it produced this error: (Sun Feb 27 00:26:32 2011) r.out.png input=raster_bulacanElevation output=...
3
votes
1answer
2k views

Is there a way of cutting a raster map that is displayed in the GRASS GIS Map Display?

I have a raster map that I generated from cropping/masking from a bigger raster map. It produced a map with only a portion of not null values. I only want to have a map that is zoomed in to the ...
12
votes
2answers
5k views

Difference between Geoserver stores: ImageMosaic, WorldImage, ImagePyramid

What are the differences between the Geoserver stores ImageMosaic, WorldImage, and ImagePyramid? I noticed that ImagePyramid is no longer included in the latest Geoserver. Is one of these more ...
6
votes
1answer
643 views

Extract many or clustered cells attributes around points using SAGA GIS?

My question is similar to Extracting raster values at points using Open Source GIS?, but perhaps more complex. How to extract the attributes of clustered cells around a point/points? For example,...
11
votes
3answers
5k views

R: Download a large DEM, change projection, and adjust to smaller scale

This is a process that takes just a few seconds in GIS software. My attempt to do it in R uses a large amount of memory then fails. Is there something wrong in my code, or is this just something R ...
9
votes
2answers
6k views

R: overlay a line on a raster stack/brick, and get profile of cell values along the line

I've combed through R's raster functions and vignettes and can't seem to get this working. I want to specify a line/vector across a raster stack (a DEM and possibly related variables), and get a ...
2
votes
2answers
326 views

Why are results all black using gdalwarp via QGIS?

I'm trying to convert a bmp image in BNG to WGS84 using gdalwarp (via QGIS). It seems to be running without errors but the output is all black. What am I doing wrong?
5
votes
2answers
7k views

Combining two adjacent raster datasets

I am trying to figure out how to combine two adjacent rasters into one raster using ArcMap 9.3.1. The problem I am having is that there appears to be a gap in the data. I would like to be able to ...
6
votes
1answer
6k views

Watershed Delineation

I am trying to delineate just the catchment area of some lakes, and am wondering the correct way to do this. I already have a filled DEM, along with a flow direction and a flow accumulation raster. Is ...
7
votes
3answers
4k 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 didn'...
1
vote
3answers
7k views

Python code to read metadata from raster file [closed]

Can you provide me with Python code to read metadata from a raster file?