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

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Extracting raster values with polylines in QGIS

I have a polyline shapefile that represent a road an a raster grid with slope values. Is it possible to interpolate the shape file and the grid to have the average slope of the road? I know that I can ...
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41 views

How to digitize RGB TIFF automatically

Is it possible to digitize RGB TIFF by color - I need to select all the vegetation cover types from the image below, which is a part of an aerial photography of an island ...
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39 views

QGIS raster calculator using abs() function

Is it possible to use the Abs() function in the raster calculator in QGIS? I've tried it, but it didn't work.
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87 views

How to convert float to raster in QGIS

I have downloaded bathymetric data into QGIS. In order to use it I need to conduct a float to raster conversion. I have not been able to find how to do this on any of the forums. I have unsuccessfully ...
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44 views

Error on 'Extract raster values to CSV' in batch process in QGIS

The Extract values (csv) contained a bug in the script. The below link shows how to correct the bug. Error on 'Extract raster values (CSV)' - Error executing algorithm 1 'Dataset' ...
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95 views

How can I get my georeferenced TIF file to rectify?

I have added a TIF file (size 1,433 KB) in ArcGIS 10.2.2 and defined numerous georeferencing points, with the aim of creating a raster file for conversion to polygons. However, on clicking the ...
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44 views

What kind of methods are most commonly used to interpolate a relief?

I have got a topographic plan with height measurements which I converted to point shape file with height value in attributes. I was wondering, what kind of methods are most commonly used to ...
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48 views

European road usage statistics per highway

I'm looking for an open data source which features the amount of cars per road per day or per year for Europe(!). I've found several national reports, which are only available as PDF and as such a not ...
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46 views

How can I transform raster to vector in ArcGIS?

I want to convert from raster data to vector dataset using ArcGIS. Raster data consists of pixels and center of z values. Vector data sets consist of points, lines and polygons and x,y values. When I ...
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15 views

Calculation of RMS between two grids [duplicate]

I want to calculate the RMSE of two grids based on their z-value: a calculated and a reference grid. I do have the statistics: Cells, Range, Min, Max, Sum, Mean, Variance, St.dev. How could I solve ...
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62 views

Error on 'Extract raster values (CSV)' - Error executing algorithm 1 'Dataset' object has no attribute 'mapToPixel' See log for more details

I would like to extract raster values at some locations (point shapefile) in 'csv' format. I use 'Point Sampling Tool' and it works well for a raster file. However, I have hundred of raster files ...
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60 views

How to create header files for multiple rasters in R

I have nearly 1000 generic binary images, i.e., headerless, band sequential and binary (16-bit signed integer). I have been succesfully able to load these with package 'raster' only when I create an ...
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49 views

Adding a grid and selecting random cells from spatial polygon in r

I have a fairly similar question to this: Similar Question I am working with a map of Denmark or more a subset of a Denmark Map. This file comes from the Global administrative areas site GADM site ...
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38 views

Combining raster images? [closed]

I've decided to work on GIS implementation in transportation. I've these small tiles of images, with world files. I want to combine them to create a base map. I don't know coding/programming, so ...
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2answers
38 views

Get raster expression

In Arcmap I have made a new raster with ArcToolBox -> Spatial Analyst Tools -> Map Algebra -> raster calculator. Now, months later, I have forgotten the source formula expression. How can I ...
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88 views

Getting Uncompressed Size of Raster using ArcObjects?

How can we get the Uncompressed Size of a raster as shown in the layer properties below using ArcObjects?
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120 views

Why covariance values are different in R and ArcGIS?

I've calculated covariance between 7 rasters using R and ArcGIS. It gives me different results. Each times covariance values from R are approximately 1.874 times higher than ArcGIS values. R - ...
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67 views

How to create the attribute table for a raster that was produced by the Slope Tool (ArcGIS10)?

I use the Slope Tool (Spatial Analyst Tool – Surface) of ArcGIS10 by ASTER GDEM (that was exported to UTM projection). The program produce new raster (with slope value), but the resulting raster ...
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How to combine raster and attribute table in QGIS?

I have some rasters representing string categorical variables. Each raster contains integers, used to translate the categorical variables. I have also the .csv tables giving the meanings of the ...
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63 views

How to correctly render a raster Layer to GTiFF with QGIS python console?

I am trying to render a map from a raster layer. As recommended in pyqgis cookbook and here(osgeo.org) I use QgsMapRenderer(). I am able to produce a picture but it has not appropriate extent and ...
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84 views

Export raster from QGIS 2.4 to PostGIS

How can I export a raster file out of QGIS (version 2.4) into a PostGIS database? I am looking for a module or python script.
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53 views

Converting rasters to polygons through cell centers

With arcgis, it is possible to convert a raster image to a polygon representing the boundary of the raster using the Raster To Polygon tool. The output polygon will follow the cell edges of the ...
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19 views

Changing extent on a raster in QGIS

I rasterized a shape. The resulting raster (lets call it raster 1) has a different extent. I made a virtual raster with the original polygon and I tried to multiply the virtual raster with raster 1 ...
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23 views

DEM error when trying to do topographic correction in GRASS

I'm new to GRASS gis and I'm trying to do a topographic correction (i.topo.corr) of 9 ASTER bands using SRTM dem. I keep getting this error message: ERROR: Illumination model is of CELL type Is ...
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69 views

Underwater terrain modeling

My task is to model the surface of a lake bed, calculate volume of it and visualize it as 3D a surface. I have acquired depth measurements in a small lake using echosounder. The precision should be ...
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40 views

Is it possible to create one raster elevation layer from two different point layers in QGIS?

I have two layers with X,Y,Z data. The data overlay only partly. Is it possible to create one raster layer with elevation data using the 2 sets of data but without merging them first?
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90 views

Stretched raster symbology not working in ArcGIS for Desktop?

I have some DEM rasters (from the same data source so I think they're uniform in all file specifications) that I'm symbolizing using the same stretched color ramp. I set the stretch type to min-max, ...
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How to get for a given pixel the values from different overlapped rasters?

I have a few rasters representing different soil properties, like soil pH and sand content. The rasters overlap perfectly, have the same dimensions and same coordinate reference system. I would like ...
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60 views

Create Georeferenced Raster For JPEG file with Mapnik Python

I am able to use Mapnik generate_image.py to generate image with a BBOX and projection. Also, I have added a python script to generate a JGW file. But to completely georeference the generated image. ...
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51 views

How to calculate area of respective pixel?

I wants to create NDVI Map, In which it shows an area of respected pixel value lies in map.I have NDVI value within -0.6 to 0.7. Suppose,I wants to calculate area of 0.5 NDVI value with scale of ...
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82 views

Failing to merge rasters in QGIS

I am new to QGIS but have some familiarity with other GIS software (namely ArcGIS). I want to merge a number of LiDAR digital elevation model (DEM) tiles (specifically, 30 individual tiles) to ...
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38 views

How I can create a raster and have the same overlay as another raster in QGIS 2.4?

I have made a graphical model in QGIS 2.4. I have to create a raster equation to rasterize a polygon shapefile. I want to rasterize my shapefile and I want to ensure that this new raster will ...
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32 views

ArcGIS Viewshed's show no visibility to south east

I'm using ArcGIS 10.2.2. I've been running some viewsheds using DTM files from EDINA Digimap and data that I've imported using .csv files. These files only contain the X Y details and a code for each ...
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129 views

How to create a catchment from a point using a DTM raster in QGIS?

I need to find a better way to delineate a catchment from a given point on a watercourse using a DTM - currently I am either using FEH, or if the catchment is too small using contours to draw ...
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110 views

Combining two overlapping rasters (combine cells, retain both values) using ArcGIS for Desktop?

Using ArcGIS 10.2, I am trying to combine two rasters which are identically overlapping in shape and extent, but with different values and counts. As an end result I would like each cell to retain ...
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71 views

Geostatistical Analyst raster export looks completely different

I'm having trouble trying to re-create how a Kriged layer looks when interpolated using Geostatistical Analyst. I like the level of generalization (smoothness) of the filled contours in the ...
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3answers
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Mosaic to New Raster tool fail

I'm trying to merge 24 DEM files, after applying the tool (Mosaic to New Raster) only 11 out of the 24 merged. All the original files are in the same projection, pixel type, band, etc. I also ...
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Python and gdalwarp: change resolution of raster

I am new to GDAL and have been having some hard time figuring out how to change a raster's resolution and how to align it to another existing raster. I have come to the point where I have a raster ...
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199 views

Example of a “bleeding” raster in GIS?

I was reading an ArcGIS Help page recently on Polygon to Raster (Conversion) GP tool. There is piece of information there that I became interested in: If "bleeding" or stripes occur in the output ...
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42 views

Different ST_AZIMUTH results for ST_PROJECT points along the same original bearing

I'm trying to develop some way of determining line of sight (LOS) between two geographical points about 1km apart or less using ST_3DINTERSECTS or something similar. BASIC PROBLEM: Along the way, ...
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99 views

Convert ESRI Shapefile to Raster using R - biggest polygon area to raster cell value?

I want to create a raster from an ESRI shapefile. Multiple polygons may exist in one raster cell. If so, I want to assign the attribute variable which occupies the biggest area of the raster cell. ...
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25 views

Finding DEM/HIllshade sources California

Creating watershed maps for schools. I want to color ramp the elevation to show low and high points. What kind of files do I need and where to find them?
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42 views

How to calculate percentage area cover using Focal Statistics

I am trying to produce raster outputs in ArcGIS for later use in MaxEnt to model species distributions, and want to produce variables with statistics on the percentage cover of different habitat ...
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46 views

Kriging with Raster Data in ArcGIS

I have MODIS satellite imagery that depicts a range of surface temperatures. However, many of the cells are missing values. I think I need to perform Kriging in order to obtain an average value for ...
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69 views

Batch Conditional Test - For Loop with a Group of Rasters

Edit: Question was answered. Please scroll to see fixed script. Thank you everyone who helped! How do I ask a “for loop” to operate on groups of three files folder (e.x. files A, B, C), then files ...
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34 views

Preserve polygon boundaries when vectorizing a raster according to a polygon vector

I have a raster which I clip by some polygons and then convert to polygon. I would like to obtain the same number of polygons in both my vector files. The problem is that some areas in the vector ...
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Urban Heat Island USING ENVI

I have downloaded MODIS images for a specified area.. Its my first time that I am working on UHI (Urban Heat Island).. I need to know the methods to work on it.. I am using ENVI for this.
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Why does my clipped raster seem to be slightly moved?

I'm having some problems with clipping rasters. I started clipping my raster using extents, but I saw that the clipped raster is different from the original raster. I created a virtual raster to use ...
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73 views

How can you create a depth raster from a DTM and a polygon in QGIS?

I have a DTM raster and a flood outline in polygon format - how do I create a depth raster for the flood outline (i.e. flood level minus DTM level)?
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57 views

how to calculate area verses each NDVI value?

I created an NDVI map, I want to calculate area of vegetation verses the respective NDVI value of the given map. Which tools are used for this process and what steps are required?