Tagged Questions

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

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3
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1answer
96 views

Why does Save as “Rendered Image” change the raster styling?

Rasters exported from QGIS (via Save As > Rendered Image) do not retain original styling. See attached. Any thought on how to prevent this error? The top image is exported from QGIS as a .bmp, the ...
1
vote
2answers
68 views

View an .ecw-file in QGIS 1.8.0? [duplicate]

I have got a .ecw-file that I want to somehow import into QGIS 1.8.0. Is there a plugin that I can install that can help me do this or is there another way? The .ecw-file contains rasterdata.
2
votes
3answers
1k views

Clip a raster using a shapefile into multiple rasters?

I have a raster file representing a large area and a shapefile of 30 polygons representing watersheds. I would like to clip the raster with the shapefile to create 30 rasters representing each ...
0
votes
1answer
85 views

Topo To Raster executing but not creating the raster

I am using Topo to Raster by File (ArcGIS version 10.1) via arcpy on a large stream and point dataset. Arcpy runs fine and executes without issuing any error message, however it does not create the ...
0
votes
1answer
64 views

Attribute names being truncated during extraction

I have 30-40 raster layers and each raster has approximately 40 columns. The attribute/column names are very long, and the beginning of each column name is the same. During the extraction process, ...
1
vote
1answer
134 views

Converting a raster to a polygon

I need to convert a raster into a polygon, and I ran into "Error 000863: Invalid GP Data Type" After searching, I saw this solution online. Basically I needed to convert the float raster to an ...
0
votes
3answers
60 views

ArcGIS - ModelBuilider - Collect Values not working as expected

I am trying to iterate through a folder of rasters, reclassify each raster, then combine all of the reclassified rasters using Cell Statistics (to get the overall SUM of the reclassified rasters). I ...
1
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0answers
75 views

Write raster with its attribute table and symbology

I am classifying lots of rasters and I'd like to automate the legend creation and symbology displaying for easy manipulation. Here is the kind of raster I'm dealing with: library(raster) r <- ...
1
vote
2answers
205 views

How to change raster cell values within a polygon using QGIS GUI?

I would like to know how to change the values of raster cells which are within a polygon, leaving all cell values outside the polygon unchanged. I would like to subtract 1.5m from each raster cell ...
1
vote
2answers
129 views

QGIS howto create raster from map canvas easily

i have question ho to create raster from QGIS map canvas (what i seen in my qgis) easily. Now i have used print composer and after some luck i get whole dataset into map item, after that i throw lucky ...
0
votes
2answers
229 views

Batch merge large numbers of.asc grid files

I have >2.5k .asc grid files which I need to merge into a single overarching dataset. I would like to avoid having to convert them into esri grids first so was looking to use QGIS (v.2.0). I am ...
0
votes
2answers
77 views

Is it possible to alter raster values without Arcpy? [closed]

I'd like to be able to alter raster values, through fairly simple equations, without using the module Arcpy. Is that possible? It seems like gdal, numpy, and rasterlang might make this possible but ...
2
votes
3answers
599 views

How to get count of non-NA raster cells within polygon using R

I've been running into all sorts of issues using ArcGIS ZonalStats and thought R could be a great way. Saying that I'm fairly new to R, but got a coding background. The situation is that I have ...
0
votes
1answer
177 views

QGIS 2.0 Howto copy raster data from a QgsRasterDataProvider to an OpenCV matrix

I'm hacking the half day arround a problem and that I' thought it was simple one. I'm using C++ (QtCreator) QGIS 2.0 und openCV2 on an 64 bit Workstation runnig Debian Wheezy. The Application I try to ...
2
votes
0answers
146 views

How to best intersect vector data with raster data?

I have Open Street Map [OSM] data imported so that I can access the geometry of buildings. I have also loaded SRTM digital height data from NASA from a GeoTIFF raster. I have projected the raster into ...
2
votes
1answer
138 views

Analyse slope gradient from LiDAR .asc data

I'm new to using QGIS. I have purchased some LiDAR data which downloads as .asc format, is there a way to analyse the terrain slope angle from this data or does it need to be converted into DEM? ...
1
vote
3answers
154 views

How to create a multi-colored raster image based on long,latt,color information?

I want to create a multi-colored raster layer to overlay on my map in OpenLayers I have the following information in my DataBase: D_Cell_ID Long Lat ColorCode 055113 ...
4
votes
1answer
83 views

Cutting Raster using two Polygons as Masks

I am trying to cut this raster in order to drop the outside of the walls white area and the area with the dots. I made one step using as mask the green polygon but i couldn't remove the inside of the ...
1
vote
0answers
239 views

TIN to Raster Tool, output elevations are 3.40282e+038 and -3.40282e+038, tried calculate statistics didn't work

I have an input TIN file that I created using Create TIN. The elevations are all correct. When I convert the TIN to Raster using the tool, my output elevations are 3.40282e+038 and -3.40282e+038 ...
2
votes
0answers
41 views

Can I clip raster maps by vector boundaries on fly while serving them via geoserver?

I have a lot of georeferenced raster topographic map sheets which contain not only map itself, but some sketch elements like legends, stamps outside the map frame. I want to make seamless coverage ...
2
votes
0answers
42 views

Extract MultiValuesToPoints yields identical value for each band

I'm attempting to extract hyperspectral remote sensing data to a point featureclass using the ExtractMultiValuesToPoints ArcGIS tool. The value of each band (228 bands) should be appended as a field ...
5
votes
1answer
313 views

Terminology problem - Raster vs Grid vs Lattice

I have a question about GIS terminology - what is the difference between grid and raster and grid and lattice - in theory?? I thought, that raster is regular network and value is in the cell and the ...
1
vote
1answer
83 views

Analyzing Raster Data From Vector Layer Buffer

I am using QGIS 2.0. I have satellite images of night-time lights all over earth. I also have a vector shapefile of country boundaries including the largest cities on earth. I want to use buffers to ...
0
votes
0answers
116 views

Choose what zoomlevel to read from for mbtiles file in GDAL

GDAL is supposed to read MBTiles files and to do so, it selects the highest zoomlevel available. However, is there a way to choose another zoomlevel? i.e. override the default and go for a lower one? ...
1
vote
1answer
51 views

How to read the count of the cells with data with non “no-data” values ,in QGis?

How to read the count of the cells with data with non "no-data" values ,in QGis
1
vote
1answer
63 views

QGIS Grid Division/Grid Product etc. results are wrong projection

I have several raster grids, all 4320 columns, 2160 rows in WGS 84 projection. They are loaded from ESRI ascii files. When I use the Processing Toolbox to carry out arithmetical transformations on the ...
1
vote
2answers
264 views

convert data.frame with no lat-long info to a raster

coders, I need to read in a .txt file into R and later do some spatial analyses on it. I’m working in R. 3.0.2 on a Windows server. I load the following libraries (probably more than I need): ...
2
votes
1answer
105 views

PostGIS Raster: Outputting raster into GDAL supported file?

I have import a raster into my postGIS database via raster2pgsql. My raster tiled to 100x100. Now I'm trying to export (output) the raster to GDAL supported file (for example: PNG). Following the ...
7
votes
2answers
215 views

Finding specific pixel values ​​in ArcGIS using Python

I have a raster file containing some integer values. I need to find all pixels whose values are not defined in list like this one: l = [1,2,4,8,16,32,64,128]. Is there any easy way to solve that ...
4
votes
1answer
372 views

How to calculate total number of data cells in raster?

I am using ArcGIS 9.3 and python 2.5. My code is shown at the bottom of this post. I have a raster containing fire intensity information at 200m cell resolution. I run the script and the first count ...
4
votes
1answer
200 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 ...
1
vote
0answers
84 views

Importing GPS coordinates to extract multiple DN values in ERDAS

I have a set of GPS points (stored as a csv for now) and would like to import these points to ERDAS to find the DN values associated with each location. I am able to import a SHP to ERDAS but the ...
4
votes
1answer
362 views

How to extract pixel value counts from a raster in QGIS?

How does one go about obtaining a summary of the counts of cell values within a raster in QGIS? I know QGIS is doing this, in order to provide the summary statistics and histogram in the properties of ...
1
vote
1answer
119 views

Convert point to grid: Numbers of cells differ

In R I am trying to aggregate points data to a grid. The data for the grid (G-Econ) comes as a csv-file. In this file each row represent a grid-cell at 1x1 degree resolution and the given ...
1
vote
1answer
61 views

Should large Basemaps be stored in DBMS via ArcSDE?

As I understand it, the SDE Geodatabase provides the technology for Multiuser databases, Versioning, replication and other Geodatabase functionality. In my organisation, this could be useful for ...
1
vote
1answer
400 views

Convert polygons in shape file to a numpy array?

I have a shape file containing a number of polygons and all attributes being text. I'm trying to import the polygons into numpy as an array where each polygon is represented as unique values. I ...
4
votes
1answer
70 views

Simple way to compare ranges and distributions of species, looking for correlation and differences between ranges

As a biology student just beginning with GIS, wondered if someone could give me an idea of what tools to go about using to compare the range of 3 species that have trophic effects on one another. I ...
0
votes
0answers
75 views

How to split a raster into multiple rasters using QGIS?

I would like to know how to split a raster into multiple rasters in a single operation using QGIS. Although I can clip the raster image, it would be better to split it using a single operation. I am ...
1
vote
2answers
220 views

Can raster files from ArcGIS for Desktop be visualized in Google Maps?

I have raster files created using ArcGIS (Desktop application). On the other side I develop an application using google maps. Can I visualize those raster files somehow on google maps API?
0
votes
1answer
129 views

How do I use wildcards to work around the GDAL character limit?

I am attempting to use the 'Merge' & 'Create VRT' tools in QGIS 2.0 on a folder with 3000+ raster tiles in. However whenever I try to perform this operation the following error appears: 'The ...
3
votes
2answers
255 views

Using python to Raster clip the extent to be the same as the display?

I've been trying to figure this out for almost a week now. I am creating a tool which first needs the raster to be clipped out to the current display. I have tried all sorts of things. Below is the ...
1
vote
1answer
428 views

How can i convert a raster from continuous to discrete?

I have a tiff that is 'invalid' for a lot of tools and will not let me view the attribute table. I think this is because it is "continuous" rather than "discrete". Does anybody know how to convert it ...
2
votes
1answer
54 views

How to stop transfer of large raster into arcsde geodatabase

I have just realised that I will not have enough space on my harddrive to accomodate a raster which is being copied into an arcsde geodatadatabase. I am afraid, that if I stop the process in ...
2
votes
0answers
188 views

What are common mistakes when creating mosaic datasets?

I have a set of images taken from a unmanned air vehicle, they have lat/lngs when properties are clicked in windows, but when they are imported into ArcGIS they have no spatial reference or coordinate ...
1
vote
2answers
68 views

How can i combine the colours of one raster with values from another

I have two Tiffs with data from the same area. One is in colour and when I use the identify shows a 'color index' number (eg. 141), then Color(a,r,g,b)(eg. 255,90,255,0). The other tiff contains a ...
1
vote
3answers
186 views

Converting files for use in fragstats

To use my data in fragstats i need to convert it into a signed integer grid. I have the data in a raster format and have tried 'right click>data>export data> and setting the format to 'Grid' and it ...
1
vote
1answer
715 views

How to Create Cost Surface Raster for Least Cost Path Analysis?

I have a DEM raster and would like to carry out a cost path analysis. Among other factors such as slope, proximity rivers etc. I would also like to take elevation into consideration. According to ...
9
votes
4answers
226 views

How to determine if point is surrounded using raster processing?

I am attempting to improve a currently extremely cumbersome vector/python process for a natural hazard model. At the moment we have a lengthy script which generates distance/bearing lines from a given ...
3
votes
1answer
169 views

White lines in merged GeoTIFF files after ImageMosaicing on GeoServer

I have merged 21 GeoTIFF images using GDAL utilities. Each image is the result of merging 500 smaller tiles. I am using ImageMosaic in Geoserver but I am getting a mosaic that contains white lines and ...
2
votes
1answer
99 views

Raster topo map “collars” overlap

I am using QGIS 2.0. I have downloaded USGS 1:100,000 topographic maps which show adjacent areas. The topographic maps were digitized with the borders (I've seen them called "collars", I think) as ...