Tagged Questions

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

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0answers
36 views

How to Use GetGeomtype Gdal Python

I am just wondering what I am doing wrong when trying to use the GetGeomType. I need to focus on separating layers from a pix file. Two categories are the bitmaps(which are vectors) and then the ...
2
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0answers
63 views

Why do comparisons in QGIS 2.4.0 Raster Calculator return -3.40282e+38 aka no_data?

I tried to use comparisons as conditional statements in QGIS 2.4.0 raster calculator. My statement is: (a < 230) * 230 + (a >= 230) * a The expected result is raster a with all values lower ...
0
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1answer
18 views

Is PostGIS-2.x raster in text format (WKT) only?

I was reading PostGIS FAQ and this tutorial. From all that I can tell, it seems that PostGIS raster is a text format, i.e. WKT or well-known-text. I was wondering if PostGIS raster data are ...
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0answers
19 views

How to merge elevation from a raster image onto a shape road network with QGIS? [duplicate]

I have a shape file with Stockholms road network and a raster image with elevation data from the same area. Is there any way to merge the two somehow, either by adding the slope direction as ...
3
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1answer
84 views

How to perform raster Overlay Analysis using QGIS?

I tried to do a raster Weighted Overlay Suitability Analysis to find the best location for home lands using QGIS. Used layers are: School location (point) Crime locations (point) Road (line) Water ...
4
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1answer
66 views

Removing some bands or layers from a tiff using gdal

I have been working on a multiband raster image. It is a pix image. I need to just work on the 26 bands that are raster files and not the 4 bitmaps that are are also included in the pix image. I could ...
3
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1answer
50 views

Is there an image editor that can edit GeoTIFFs without affecting their embedded georeferencing?

I know there are a couple workarounds for this but I was hoping a direct solution exists. I am looking for an image editor (like Photoshop but hopefully free software) which can be used to edit ...
3
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1answer
42 views

How to clip vector data from raster data?

I have two files: National land cover data (raster) HUC 8 (vector files of watersheds) Both are national scale but the HUC 8 takes up a larger geographic region than the raster set so I want ...
1
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1answer
58 views

Reclassification of raster surface using ArcGIS for Desktop?

I have a raster surface with values ranging from 0 -100. I want to create a categorical classification (percentage categories of 5%, e.g. 0-5%, 6-10%...) and reclassify my surface into these ...
0
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0answers
34 views

Find correct SRID

I'm learning PostGIS raster, and importing GeoTiff with raster2pgsql. This command line tool states: -s <srid> Set the raster's SRID. Defaults to 0. If SRID not provided or is 0, ...
2
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2answers
47 views

Raster clipping without producing no data values

I'm trying to clip a raster in ArcMap using a polygon, and I'm wondering if there's any way to have the resulting raster not include any "no data" values (I apologize for the poor grammar). My process ...
0
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0answers
36 views

Setting raster resolution in meters when working in a Geographic Coordinate System

I work in WGS 84 (Geographic Coordinate System) in ArcGIS 10.1. I need to create a raster specifying its cell size in meters, and output it in WGS84. Is it a good solution (towards a less shape/area ...
5
votes
1answer
101 views

How to determine the optimal raster resolution when interpolating a surface from points?

I'm looking for guidance on how to determine the desired output resolution, when interpolating a surface from irregularly-spaced point samples. I have a series of boreholes taken across a city, and ...
1
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2answers
61 views

How does Environments > Raster analysis > Cell size works in ArcGIS?

How does Environments > Raster analysis > Cell size works, when creating a raster from a polygon using ArcGIS? I have tried to handle both "Maximum of Inputs" and "Minimum of Inputs" and nothing ...
1
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3answers
26 views

Raster statistics

In ArcMap, I have a raster layer representing site locations. I derived elevations values for the sites from a DEM. Now want stats on distribution of elevation values at those sites. How can I do ...
1
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2answers
44 views

Troubles exporting raster to tiff in ArcGIS

I am exporting in ArcGIS a raster by doing Data > Export data. But in the Export Raster Data window, I don't have the option for choosing the file format. Am I missing something? Perhaps must the ...
1
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2answers
41 views

How to set the cell size of a tiff to 1 meter when working in a Geographic Coordinate System?

I am working in a Geographic coordinate system in ArcGIS, and I need to create TIFFs by exporting rasters. THese .TIF file must have a resolution (cell size, or GSD) of 1 m. Is it possible to set any ...
3
votes
2answers
96 views

How can I extract all distinct values from a PostGIS Raster?

I am working with an integer raster in PostGIS 2.1 and I would like to extract all distinct values in that raster. I was hoping to be able to do something along the lines of the following query, but I ...
1
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1answer
46 views

How to convert raster to im object for point process model covariate in R

I am trying to convert a raster object to an .im object for use with a point process model in the spatstat package in R. I begin by creating the raster from a tiff file using the raster() package. No ...
1
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0answers
46 views

using r.volume model GRASS plugin in QGIS

I am calculating volume of bathymetric data in the form of a clipped raster in GRASS with a Custom Lambert projection centered around 70degrees North, using the module r.volume in GRASS. Side note: ...
1
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0answers
47 views

List of vector to one raster in PostGIS

Hi PostGIS developers! I need to rasterize a part of OSM map by coordinates. I found rather good algorithm, but can’t finish it. I have problems in STEP 3. I described all algorithm here – may be ...
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0answers
12 views

What do pixeltypes in PostGIS raster mean?

I'm trying to build a raster in PostGIS from a vector layer and I was curious as to the meaning of pixeltypes in the raster geometry? How does it effect my raster?
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0answers
34 views

Making grayscale map from multiple band satellite image in ArcGIS for Desktop?

I have satellite multiple band map, I needs to make grayscale map,what should i do? what is the steps? which band and format of input are to be used in this? How to make attribute table of this? In ...
1
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1answer
34 views

How to know the GSD (grid size, resolution) in meters of an existing raster when working in Geographic coordinates?

I would need to know the GSD or grid size (resolution), in meters, of a raster created when working in a Geographic coordinate system in ArcGIS. Is is possible? Even better, can I set the Cell size ...
1
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1answer
23 views

How to output the number of channels in a .JP2

I am looking for any tool (or python code snippet) that can loop through a file folder of .jp2 images and determine which have 3 bands and which have 4 bands. I am having trouble creating a raster ...
5
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3answers
99 views

Create a Raster file out of a ASCII grid file?

im using a special system to do geomagnetic surveys. Its software let me output the information as image files, ASCII or in its own proprietary file format. Now i want to get its information in my GIS ...
1
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1answer
35 views

Raster created by python GDAL interpreted upside down

I am using CRS which has axis in left bottom corner. Code below produce Geotiff which is shown allright in QGIS but when I open it in other software it is upside down. Also gdal_calc takes it as ...
1
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1answer
60 views

Export Multiple Raster Data with custom Cell Size

I Have 172 Raster, and need to change the cellsize. So I use Export Data from TOC and change the cellsize manually (example I want to change it to "3") I tried using this python script to ...
0
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0answers
21 views

Interpolating points to surface not working

I am trying to create a surface from points using IDW interpolation. Have tried both 3D analyst and Spatial Analyst tool with my selected xyz data sheet. It appears to process and I don't get an error ...
2
votes
1answer
67 views

ListRasters based on filename using Arcpy

I am trying to create a python script for ArcMap which calculates the ndvi from two raster images for each RGB/NIR pair in a folder. However, I am unsure how to create two raster lists; one which ...
1
vote
2answers
54 views

Changing raster resolution using ArcGIS for Desktop?

My raster is displaying at a very low resolution so it is almost useless. Last time I used this file it was at a much higher resolution, so I know the information is there. To change it I first ...
1
vote
1answer
36 views

Batch processing of geodatabases - join raster with table

I am unsure how to go about doing this using Python in ArcMap, though I know how to do it by hand. I have geodatabases containing gSSURGO data, one for each state, in their own folders. I have a ...
1
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1answer
26 views

Split linear features from non-linear in the same feature class

I have a vector layer (Originally a raster layer) of well sites, cut blocks, and seismic lines all lumped together in the same feature class and no distinguishing attribute between them. I want to ...
1
vote
1answer
61 views

geoserver world image publishing error (georeferenced by ArcMap)

I want to add store - WorldImage in geoserver 2.5, but I still get this error: "Could not list layers for this store, an error occurred retrieving them: Failed to create reader from ...
0
votes
1answer
53 views

Determining the slope of a DEM (SRTM-data) in QGIS

I'm new to QGIS and I have to calculate the slope of a DEM (I use srtm-data). I already detected the geoalgorithms toolbox and I also produced a raster layer with the slope using the tool "slope, ...
1
vote
1answer
44 views

Error importing raster into GRASS plugin in QGIS

I am trying to import a tiff raster file into GRASS however every time I do this the below error message comes up. I am using a custom CRS so I have tried changing it back to the default CRS but still ...
2
votes
1answer
94 views

Dealing with raster: creating it in projected CRS and exporting it in geographic CRS

When creating a raster from a polygon (the CRS of the polygon is a geographic coordinate system), the raster is created in the projected coordinate reference system of the data frame, which is a ...
1
vote
1answer
35 views

Setting resolution for GRASS raster

I am trying to calculate volume using the GRASSplugin. I have my area information in vector format and my depth information in raster. I read that it is important to set the raster resolution before ...
0
votes
1answer
31 views

Disable black background color of a satellite image in mapserver mapfile?

I'm publishing rasters using Mapserver. How to disable background color of a satellite image in map files or How to set “Display Background value ”0“?
1
vote
1answer
40 views

Making color map in ArcGIS for Desktop?

I have bands 2, 3, 4, and 5 map. How can I use these to make a color map in ArcGIS 10.1 for Desktop? Can you give me steps? Also I want to make attribute table of colormap. How this can be ...
1
vote
1answer
23 views

Difference between source SRS and target SRS in Raster Warp function

Hello I am trying to change a raster layer projections from WGS84 to a custom Lambert layer using 'Raster' --> 'Projections' --> 'Warp' function. I have been asked for source SRS and get SRS. what is ...
1
vote
1answer
46 views

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 ...
3
votes
1answer
39 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 ...
1
vote
1answer
38 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.
1
vote
1answer
86 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 ...
1
vote
0answers
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' ...
2
votes
0answers
88 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 ...
1
vote
0answers
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 ...
4
votes
1answer
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 ...
1
vote
1answer
45 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 ...