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

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“Extract by Mask” changing raster pixel values…or not?

I am using ArcMap 10.0 and am confused by my Extract by Mask output rasters. I hope to eliminate the black background from three Landsat ER Mapper images so that I can mosaic them. Originally I ...
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1answer
1k views

Extract multi values to point error

I am trying to extract values from my rasters (slope, aspect, landcover etc.) for my animal group locations. I used Spatial Analyst > Extract Multi-values to Points, but when I look in my attribute ...
2
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1answer
624 views

Create a subset of a dataset with a specific grid size in ArcGIS using Data Management Tool

I am wondering how you can create a subset of a dataset that is a specific grid size (in pixels) using the Clip tool within the Data Management Tool box for raster data. I was trying to find a hint ...
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1answer
406 views

Difference in raster size using raster2pgsql

I use the PostGIS-build-in raster2pgsql to load SAGA-raster into the db. I tried to grid them into 100x100-tiles, just as seen in the code: /usr/lib/postgresql/9.2/bin/raster2pgsql -s 32632 -a -F -...
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1answer
248 views

Assigning costs to a road network : use raster or vector?

I have a road network in a PostGis database (db_routing). In another database (db_environment), I have some spatial features of the surrounding environment (trees as points and water bodies as ...
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2answers
538 views

How to set min and max value for stretchType: esriRasterStretch_PercentMinimumMaximum

How can I set the min and max values for the stretch type "Percent Clip" in arcobjects? It's possible to set the Stretch type: rasterStretch.StretchType = esriRasterStretchTypesEnum....
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4answers
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How to reclassify a float raster?

I have three rasters which represent distance (in metres) from certain things (bus stops, parks, libraries). I would like to reclassify these rasters so that they get integer values based on the ...
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132 views

Raster area (QGIS) problem explained

I would like to know the area that each value in a raster has... The raster I have has values from 2-15 and I would like to know the area that each value is occupaying within my polygon... Thanks! I ...
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38 views

Why are areas of raster and polygon after digitization not matching? [duplicate]

I have followed the answer given in this question:How to calculate the area of rasters in QGIS? I vectorized and calculated the area using geometry columns but I a faced a strange problem. When I ...
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3answers
4k views

How to Export Raster with same classification colors seen in ArcMap?

I have a single band raster, but i like to export it with the same colors as in Arcmap. Any help please.
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Grass 7 / ArcGIS 9.3 - tiff to raster

Again a Grass 7 question. I have the output of a modelling run as matlab file, which I can export as tiff and load as geotiff. OK - now can I extract the data/convert this tiff into a raster proper? ...
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1answer
89 views

Grass7 - r.regression.multi and new raster

I am on the learning curve with Grass7. I managed to make r.regression.multi work, but there is one thing that would be of high interest for me: it is possible to create a new raster showing the ...
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1answer
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What is some theory on the number of GCP when georeferencing?

Just wondering, is it always better to have more than 3 GCPs? Should the GCPs be spread out evenly? Where can I find some general resources on the theory of this? Other than trial an error, which ...
3
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1answer
90 views

How to always see all band values with Identify Features of QGIS?

Does anyone know if it is possible to get the Identify Features tool in QGIS to show the band values for all the layers shown in the results window? To clarify, whilst I have several bands "showing" ...
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1answer
111k views

What is the difference between Vector and Raster data models? [duplicate]

From: http://support.esri.com/en/knowledgebase/GISDictionary/term/vector%20data%20model vector data model: [data models] A representation of the world using points, lines, and polygons. Vector ...
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1answer
721 views

Problem to clip a raster with a shapefile

I need to clip a rasterlayer with a vector layer. When I try this, the following error appears: **ERROR 1: Attempt to create 0x0 dataset is illegal,sizes must be larger than zero.** What am I ...
6
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1answer
671 views

raster tile - find the correct tile for a given coordinate

I have a large raster map which I loaded into postgis with 1000x1000 meter tiles... the corresponding table has about 200 rows, each row representing a tile. I want to get the raster value for a ...
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2answers
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How to clip raster by multiple polygons in multi rasters?

Using QGIS, I want to clip a raster by multiple polygons contained in a single shapefile. I read that gdalwarp can clip my raster by multiple polygons BUT the output is a single merged clipped raster. ...
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3answers
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What is a simple binary raster storage format which ArcGIS can read?

I have a C++ program that manipulates raster digital elevation models. I have been using ArcGrid ASCII format for results. It is simple to code and gets the job done, but it necessitates a decimal ...
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3answers
565 views

Which CRS would you use to georeference historical world maps?

Which CRS would you recommend to georeference historical world maps like the ones in the London Geographical Institute - The Peoples Atlas - 1920, e.g. The map displays a lat/lon grid which I would ...
3
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1answer
201 views

Differences in raster extents in gdalinfo, SAGA & Quantum after resampling

I recently resampled a raster file using SAGA's Resampling module. The aim was to widen the extent of the new raster to two decimal places, where the original raster has three decimal places. The ...
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2answers
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Reducing the resolution of a huge raster

I'm not much of a GIS user, but I've got a big ascii file that I'm trying to convert into a lat long data x1 y1 d1 x1 y2 d2 x1 y3 d3 x2 y1 d4 ... etc format, so that I ...
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1answer
161 views

Algorithm to merge adjacent raster datasets

I am trying to figure out how to merge adjacent raster datasets. Is there any clear algorithms (may be a pseudo code)?
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190 views

Display raster outlines

I guess mine is a very simple task, however I don't know how to solve it. I m trying to display the outlines of a raster created from a polygon shp. What I would like to come up with is an image where ...
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380 views

How to create raster attribute table to a raster data using gdal python?

I classified a remote sensing data and saved it as a raster using Gdal python. I want to create a raster attribute table for this classified result.. my classified raster has five classes with 1,2,3,4,...
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1answer
584 views

QGIS cannot view raster loaded to PostGIS through raster2pgsql

I tried to load a raster GeoTIFF image to a PostGIS database using "raster2pgsql" following the OpenGeo Suite Manual. The command I used is: C:\>raster2pgsql -s 4283 -I -C -M "C:\Program Files\...
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Automatically discard nodata area of raster [duplicate]

Given a raster with an overly large nodata surround, how can I automatically discard the surround? Said another way: how does one shrink the raster extent to only occupy the area containing values? I ...
2
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1answer
181 views

Can TimeManager animate a large number of rasters in QGIS?

I understand that as of a year ago, the TimeManager plugin was not intended to handle more than a handfull of rasters. This post is in blind hope that this has changed! I'm trying to create a map ...
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152 views

Searching Pixel Location (idrisi) on Another GIS

I'm Searching similar command Pixel Location (like idrisi) on Another GIS, I, need create raster file with values ​​lat, long by separately... Update: I need a raster file where the value of each ...
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1answer
1k views

How to invert polygons (or other options for exterior styling)?

I have a shapefile containing many polygons that I want to use to mask a raster. I have tried gdalwarp -cutline <shapefile> -crop_to_cutline -srcnodata -9999 -dstnodata -9999 <source_raster&...
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Overlay Vector Layer on Raster Layer

How can I overlay a Vector Layer on a Raster Layer and assign NoData Values on the Raster where the Vector Layer does not cover the Raster Layer? (preferable with ArcGIS)
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597 views

raster statistics - regressions between raster data

I have the following problem: I have two set of rasters, with data that should correlate...one are measured data, one are modelled data. The correlation is weak, however, when looked at with a normal ...
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4answers
288 views

How to clip rasterdata for later processing?

My need to dwell with geographical tools is only temporary, thus I am not well versed and my question is difficult to pinpoint exactly. But here it goes: -I have about 5-10 sites, for which I need ...
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1answer
231 views

Where is the File Geodatabase Raster Dataset file stored?

I have a esri file geodatabase with a raster dataset. How can I find out which physical file the dataset is referring to? (I am retrieving the file geodatabase through the internet. It all seems to ...
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4answers
207 views

Batch visualization of raster (grid) files

I have about 100 raster (grid) files (in the "ascii grid" format) of drought index. All cover the same area of interest but at different times of year. I need to create images from the grids with ...
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1answer
156 views

Why Stacking rasters return all values as NAs?

I have several rasters that I want to do some calculations ,basically calculating the moving average. saf class : RasterStack dimensions : 720, 1440, 1036800, 601 (nrow, ncol, ...
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1answer
445 views

Zonal Statistics-Weighting

I have a raster file on precipitation and I want to create zonal statistics as a table using a shape file wiht boundaries of countries across the world. However it appears that I need to take into ...
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4answers
671 views

How to display a “Save As” dialog for raster files?

I'm writing a QGIS plugin in python. I need to show a "Save as" dialog window in order to allow the user to select the path of the output raster file. Do I need to create a QFileDialog and manually ...
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2answers
159 views

Point file to raster

I have a point file of trees in my study area, which includes the attributes of each tree. Each tree also has a crown radius associated with it. I need to summarize the attributes of these points ...
4
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3answers
661 views

query raster cell values by point

I have a binary raster (0s and 1s) that I need to query given a set of point coordinates. This is easy enough to do with gdal (gdallocationinfo), but where it get's complicated is that I also need to ...
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93 views

Join field from table to a raster layer

I'm trying to join a field in a table to a raster layer. I'm using the tool 'Join Field'. The table is in a excel sheet, but have been imported to a file geodatabase. The table has an ObjectID field ...
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1answer
104 views

BIOMOD Error message: argument of length 0

I’m using the package BIOMOD in R to modelling habitat in rodent species. The data formatting works but I'm getting this error message when I run Modelling: ## Conputing the models ## ...
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121 views

Creating Raster with values based on function output

I have a function that calculates a price based on the input slope and distance. I want to write the price to a raster as the rastervalue. How do I do that? OpenSource and ArcMap solutions would work. ...
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3answers
3k views

How to make polygon from cells of a raster?

I have 100 rasters, each raster has the same cell size and extent and i want to make a polygon of each cell. Can anyone help me doing this?
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1answer
280 views

Can you use a large file directory of jpgs for without georeferencing

I have a large map data set of 256x256 jpg images. The file directory is organized by /map_type/zoom/x/y.jpg. I have 12 zoom levels and each zoom level directory has 2^(2*zoom level) images. I have ...
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2answers
488 views

Making Shaded Area Polygon from HILLSHADE raster in ArcGIS Desktop?

How am I suppose to extract the values ( Value<=100 ) from this HILLSHADE raster, and then make the extracted values as a VECTOR POLYGON (shapefile) ---I'm using ArcGIS 9.3 (ArcInfo with all ...
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2answers
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GDAL does not ignore NoData value

I am trying to calcualate the statistics of a TIFF. The script should ignore the NoData value, but doesn't. What causes this? import gdal from gdalconst import * # register all of the drivers gdal....
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arcpy adding time to Raster Mosiac Footprint

I am trying to create a raster mosiac for use in animating data over time. The current workflow is: Create .gdb (arcpy.CreateFileGDB_management) Create Raster Mosaic (arcpy....
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4answers
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Garmin etrex raster maps support

I currently use an excellent set of printed topographic route maps for mountain biking. I would like to scan the maps, georeference them, and upload the maps to a handheld GPS device. Does the etrex ...
4
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1answer
363 views

Polygon to Raster taking longer in script than in ArcMap?

I have a large dataset that I am working with. Basically I have a table with 900,000 records that I join to a geodatabase feature layer, then convert that to a raster. This process takes a total of ...