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

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48 views

How are kappa and overall accuracy related with respect to thematic raster data?

I recently calculated kappa (using confusionMatrix{caret} in R) between a thematic raster dataset at 1m spatial resolution and another at 30m spatial resolution. I was interested in quantifying the ...
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14 views

Multiply Rasters with Scalar Numbers as Input in QGIS Modeler

I built a little model in the QGIS modelbuilder which uses the raster calculator with the command gt(a,threshold) I need to run the model with varying thresholds from 2 to 30 so it would be ...
3
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2answers
111 views

How to generate wind direction raster using its U and V components in arcgis?

I have two raster layers representing the U and V components of a vector wind. I could generate the magnitude raster by applying (u*u+v*v) in Map Algebra in ArcGIS. Now I need to generate the ...
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1answer
113 views

QGIS GRASS Missing Dependancy

I want to perform a view shed analysis in QGIS using GRASS 7 r.viewshed. When I double click on r.viewshed in GRASS GIS 7 commands in the processing toolbox of QGIS I get the following message: ...
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1answer
18 views

Problem with batch mode Saga Raster Calculator

I have to do a couple of raster multiplications for which the batch mode would save me a lot of time. But the only thing I get are rasters that contain nothing but nan values. If I multiply the ...
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17 views

Easy way to extract raster cells OUTSIDE a vector (Mask) layer in QGIS?

I have a raster file but am only interested in the cells outside a certain polygon. This polygon is very iregular and scattered across the raster. Is there any easy way to extract only the cells ...
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1answer
62 views

Levelplot(RasterVis) two marginal plot scale?

How can I add/display scale to two marginal plot? RAD1998.all <- stack(list.ras) list.files <- mixedsort(list.files(paste(getwd(), "/1998bil/", sep = ""), full.names = F, pattern = ...
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1answer
32 views

Deleting vector lines beyond image extents using QGIS?

I am using QGIS 2.2 I have one vector line layer (roads) that stretches beyond my base image (see below). I wish to have the roads "clipped/trimmed or deleted" right at the edge of the image's ...
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1answer
13 views

How can I shift raster layer for making cloud-shadow mask?

I want to make cloud shadow mask in QGIS. I have raster cloud mask and I have to shift it by X,Y coordinates. Is there any easy solution? Many thanks, Helena
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27 views

Graphically depict statistical difference between thematic rasters

The graph shows a regression between two raster datasets with classified tree canopy cover: class 1 = 0-10%, class 2 = 10 - 20% ...class 6 = >60% (Figure 1, Figure 2). The spatial resolution for ...
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15 views

splitting polygons by semi-automated classified raster and into multipolygons

I am studying glaciers. Most of them in my case are partly covered by debris (i.g rocks) and partly not. So I ran an automatic classification to recognize these two type of coverages and produced a ...
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1answer
48 views

levelplot index issue

levelplot with static index works fine but not in a for loop. What's wrong with my code? Static index: png(paste("1998",outlist[[1]],".png",sep="")) levelplot(RAD1998.all[[1:4]]) dev.off() ...
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58 views

R -plot 12 images per plot or save 12 images per image file in R

Here is R script and my question is How can I plot 12 images per plot or save 12 images per image file because I have total 864 images. RAD1998 <- raster(paste(getwd(), "/1998bil ...
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1answer
33 views

AttributeError: 'unicode' object has no attribute 'save'

I'm trying to multiply my raster to 100 from my ListRasters. I've adapted the code (especially the for loop portion) also from this site. Now, I'm encountering an error at the last line, when saving ...
2
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1answer
131 views

Highest DEM pixel in polygon

I'm working with QGIS and have a big DEM raster layer with height information and a vector layer with many polygons, representing 1 x 1 degree tiles. Now I want to find for every polygon the highest ...
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0answers
36 views

(How) can I write string data to a raster with Python/GDAL?

In Python, I have a NumPy array of string values (categories of some variable) that I'd like to write to a raster file (.tif or .img) using GDAL. The impression I get is that it's not possible to ...
2
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1answer
14 views

QGIS raster clip error: Cutline not of polygon type

I have a raster file and want to clip it, but I'm getting this error: "ERROR: Cutline not of polygon type" what does this error mean and how can I resolve it?
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21 views

Align & Sum Grids in Python

I have two grids. One, call it A, is 4320x2160 cells and spans the whole globe. The other, call it B is 8640x3432 and spans the circumference of the globe, but is clipped toward mid-latitudes. Both ...
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2answers
35 views

Reclassify a rasterList and sum the reclassified value from each Pixel

I'm trying to write a script in arcpy which reclassified a List of Rasters. This rasters are made by another tool before so there is already a loop. Actually I get the error 000582 and before this ...
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1answer
33 views

How can units be defined in QGIS for the Rasterize tool?

I am using QGIS 2.4 (Chugiak) via the kyngchaos build for OS-X. My question is--when using the Rasterize tool to convert a point vector layer to a raster and using the "Raster resolution in map units ...
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0answers
26 views

PostGIS Raster functions not working

Hopefully I have a simple question that I'm not phrasing correctly in google. I'm trying to learn about storing and producing rasters in PostGIS. There are tons of examples and documentation online ...
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1answer
17 views

Java how to create geotiff from points

I have an array of objects where each object has three fields: lat, lon, and category. It is essentially pixels that have been given a land use category. I cannot figure out how to turn this data into ...
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32 views

Looking for a QGIS solution to make aerial imagery ArcSDE compatiable

Would like to avoid having to use 3d Analyst and use free raster tools in QGIS or elsewhere to make aerial rasters ArcSDE compatible. This 18 page work flow is what I am trying to use. Any suggestions ...
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1answer
48 views

Speeding up loading raster

I georeference a tif image and then I clipped that image in a mosaic. I did a index of these images but when I load them is very slow(7 seconds or more to display the first tile). How can I do to go ...
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1answer
27 views

Error reading large virtual raster with rasterio: “Cannot invert degenerate transform”

I've created a virtual raster using gdalbuildvrt, which covers a large extent (England) at a high resolution. The data is fairly sparse, focused around the coastlines with no files covering inland ...
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27 views

How to smooth raster data? [duplicate]

I want to print a map of an island based on SRTM data but the basic raster layer looks pixelated especially at the transition to the ocean. Is there a way to smooth it?
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65 views

Correlation between point feature (disease) and elevation

I have a problem! How can I calculate the correlation between point feature and Dem raster? Hypothesis: disease prevalence in high altitude is more than low altitude. I must do this in ArcGIS 10 and ...
2
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2answers
29 views

Setting background RGB value to invisible for multiple rasters in ArcGIS Desktop?

I'm using ArcGIS Desktop 10.0. I need to set my background rgb value of 255,255,255 to transparent. In the layer-Properties Windows > Symbology I can do it for one layer, but can I batch set this, or ...
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1answer
57 views

how to use gdal_rasterize? how to know which attribute to burn with ogrinfo?

I have a vector layer I need to rasterize. I guess this is a basic operation, but I haven't found the information I need yet. First, I have reprojected the vector shapefile: ogr2ogr -s_srs ...
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0answers
40 views

Is it possible to change the default raster style of newly created rasters in QGIS?

If I do calculations on rasters with the raster calculator or other tools, the resulting rasters displayed in my canvas are always in the same default style (singleband gray, black to white...) so ...
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39 views

How to add a TIF raster layer programmatically?

This is my code whenever i try to load .tif image it shows layer is not valid,QgsRasterLayer always return invalid layer (I am using linux 12.04). QString myFileName = ...
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26 views

How to group a multiple rasters in MapServer?

I had a map files for each state (raster file) of India. Now I want group all mapfiles to show a single raster or single map file? How I can do in using qgis or any platform?.
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45 views

Is there raster equivalent to vector Intersect?

The intersect tool that is used on vector data cannot be used on raster data. What tool can I use for my two rasters that does the same as the Overlay > Intersect tool?
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1answer
27 views

Determine changes in land cover of isolated features over time?

I have a a study area of 2 Landsat scenes from 2013 which were classified for a specific natural community, and these areas have been isolated and extracted and digitized into vectors so that they can ...
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29 views

Merge/mosaic categorical rasters in QGIS/GDAL

I am attempting to make yearly bins of some monthly MODIS data for all of the US. The cells of the raster are defined with Julian dates indicating the date at which a burn event took place. After ...
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2answers
57 views

Use Values from Raster Statistics (e.g. sum of all cells) in Raster Calculator

I need to do calculations on raster layers which require the sum of all cells of the raster. I've used the zonal statistics tool for that but it gets a little annoying to do those extra steps (run the ...
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1answer
34 views

Con() does not recognize raster values

I have a problem when using the con() argument. What I want to do is to remap all raster of a raster file ("Red_SL") cells with values larger than 40 to the new value 5. All other values should be ...
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1answer
33 views

Iso Cluster tool in script failing to open clip raster

I have been coding in Python for only a few months, so maybe I'm just overlooking a minor detail as a newbie. I have written the script below for a class project. It is supposed to clip two rasters, ...
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20 views

Problem with adding mosaic layer via arcpy

I have a mosaic layer that I want to add to my map in ArcMap. When I add this layer manually (i.e the "Add Data" button), a raster image, a boundary, and a footprint are added to my table of contents. ...
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1answer
28 views

Cannot get 2 raster files of same cell size to align ArcMap 10.2

I have two raster files that are the same cell size but I cannot get them to align properly. (I want the black to line up with the pink) When creating the black raster file (from using polyline to ...
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1answer
125 views

How to find the projection of an image?

Instead of georeferencing the image and deforming it, I'm trying to find the projection used by the author of the image. I've got tens of these distribution maps to digitize. The idea is to avoid ...
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3answers
52 views

Use GDAL command line to copy projections

I have two images, a georeferenced Tiff and a second Tiff without a reference. The second image is a copy of the first, but it lost its reference. Now, I want to copy the reference from the first Tiff ...
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2answers
59 views

QGIS Raster Calculator: Need values to be set to 0 instead of no data

I have a landcover map with different values for the landuse options e.g. 190 for commercially used areas. Now I want to extract only these areas using the Raster Calculator with the expression ...
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3answers
65 views

Zonal Statistics as Table Tool

I have a slope dataset. I have a polygon shapefile with territory within the extent of the slope map. I have to calculate the real surface area of this shapefile using the zonal statistics as table ...
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45 views

Raster Calculator

I have a slope dataset. How do I calculate the real surface area for this slope dataset using the raster calculator. This is the example I was given: orthogonal area of a raster cell in square ...
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12 views

Raster Analysis Grid (Interpolation) Crashes

Upon clicking on "Grid (Interpolation)" QGIS crashes. I running QGIS 2.2.0-Valmiera on a Mac with OS X 10.9.4 Thank you for any trouble shooting guidance
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33 views

Polygonize Missing Polygons

Polygonize is not capturing all of the pixels in an image that has been converted to 0s & 1s. The pics below show -original geotif -geotif recalculated to 0s & 1s -polygonize output As the ...
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1answer
58 views

data source for worldwide cross-sections of topographic and bathymetric for woodworking art project?

i am a decent r programmer and statistician, i am able to work with data sets pretty well. i am less familiar with GIS tools, but if given a shapefile i can certainly plot political borders and ...
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29 views

Positioning and tracing polygons over an image

On QGIS 2.0 - I want to add an image (TIFF or whatever) then resize and correctly position it over a satellite image (openlayersplugin). Then, the task is to create a new shape file layer and draw ...
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2answers
28 views

polygon to raster - not all polygons rasterized

I have a building footprint shapefile (polygons) that I want to convert to a raster. I use the Polygon to Raster tool, and specify a cell size by importing from another raster (which is 24m x 30m). ...