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

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How to calculate the flood volume using a LiDAR DEM and a HEC-RAS floodplain polygon

I’ve got a vexing GIS analysis problem which is conceptually fairly straightforward, but in reality more challenging to figure out…. Basically, I need to calculate the VOLUME of floodwater within a ...
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3answers
355 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 ...
2
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2answers
677 views

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 ...
0
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1answer
115 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)?
2
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1answer
83 views

Displaying raster attributes on data driven pages

I have a feature class of 50 properties that are ranked. I have a photo for each property stored in a raster attribute column (in the feature class) called "Picture". I am trying to create a Dynamic ...
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3answers
357 views

Unattractive image artefact when exporting from QGIS's Print Composer

When I export my map from Print Composer in QGIS 1.7.4, an odd red band appears across the middle of the image. This happens when I export to both PNG and PDF. Its not visible on the screen before ...
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76 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 ...
9
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1answer
2k views

Differences between Raster Dataset, Raster Catalog, and Raster Mosaic

I have about 40 scanned, colorful Geology maps that are GeoTiffs. I want to bring them into an Esri FileGeodatabase to lower their size, combine them as one and display them with a mostly transparent ...
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380 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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4answers
551 views

Dikes extraction from DEM

I do have DEM of 1x1 meter and original LiDAR point cloud in .las, that DEM is made of. I need to extract river dikes (highest points of the dikes) to vector feature (point, polyline). Any idea for ...
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616 views

ArcGIS 10 - disappearing rasters?

From time to time it happens to me that rasters disappear at certain zoom level in ArcMap, or only some parts of the raster (strips) show up. I'm working on WinXP, ArcGIS / ArcView 10, Sp2, rasters ...
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85 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 ...
2
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1answer
85 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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0answers
33 views

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 ...
1
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1answer
377 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 ...
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2answers
390 views

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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1answer
138 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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1answer
271 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
128 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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105 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. dir2 <- list.files("D:\\2010+2011", "*.bin", full.names = TRUE) ...
3
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1answer
83 views

V.kernel not working correctly in grass-6.4.2

I am using grass-6.4.2 for generation of heat maps of crime data. For testing purpose, I created a vector layer from my places shapefile which is a point data.The places shapefile contains more than ...
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1answer
224 views

How to convert a shapefile polygon to raster in C#

Does anybody know a way to convert a polygon (vector) in a shapefile to raster data WITHOUT using ArcGIS Explorer Desktop? Is there a way to do this 'progmatically' in C# (WPF with ArcGIS runtime ...
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70 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
68 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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1answer
93 views

d.rast.edit error when attempting to edit a raster

I always get an error when I try to edit cell values in a raster with the GrassGIS command „d.rast.edit“. The error under Windows XP/GrassGIS 6.4.3 says: Exception in thread Thread-29: Traceback ...
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88 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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1answer
180 views

Why is transparancy of GRASS rasters missing when imported into QGIS?

I have a raster map in QGIS imported from a GRASS mapset with the QGIS GRASS plugin. The problem is that I have null() cells in the GRASS map that appear "colored" in QGIS. How can I set the ...
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1answer
137 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 ...
3
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2answers
566 views

How can I apply stretch in ArcGIS 10 Image Analysis Window?

I need to apply stretch to ArcGIS 10.1 exported raster. The best way to accomplish this task: Image Analysis Window, because there are fine tools to equalize raster data. 1 - This is my IRS-P6 24m ...
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2answers
197 views

Make a “Shaded Area Polygon” from HILLSHADE raster in ArcInfo 9.3

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 ...
4
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2answers
722 views

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 ...
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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
225 views

How can I avoid reprojection gaps when merging DEM rasters?

I have two raster DEMs in same resolution I want to bring together. I was using the merge-function in SAGA, GRASS and QGIS but I always get the following result: What do I need? Where could the ...
2
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4answers
1k views

ArcInfo Grid ASCII to ESRI Shapefile conversion

I have an ArcGIS grid ascii file (Ramankutty Cropland at 5 minute resolution) that begins as follows: ncols 4320 nrows 2160 xllcorner -180 yllcorner -90 cellsize ...
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1answer
425 views

How to replace values in rasters in directory 1 based on condition on other rasters in another directory?

Having 10 raster files in one directory and another 10 rasters in another directory and both have the same dimensions. directory 1: files1 <- list.files("C:\\2010", "*.envi", full.names = ...
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306 views

Using ArcGIS to filter cells where 7 or 8 of the neighbors are different

I have land cover data that I would like to clean using some generalization tools. Majority filter does almost exactly what I want, but is missing one key option. Majority filter allows you to change ...
3
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1answer
157 views

Polygon to Raster is 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 ...
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313 views

Are there any examples of WCS getcoverage requests done using ajax?

I am looking through openlayers to try to figure out a consistent format for generating views of coverages that can satisfy any wcs server, but mainly I'd like to get geoserver coverages. While I've ...
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1answer
142 views

ArcGIS 10 rasters/features in ArcGIS 9.3

I am tempted to go back to ArcGIS 9.3 from ArcGIS 10. For what I do, 9.3 is more efficent. Now...I know I cannot open ArcGIS 10 documents (maps, scenes) and layers in 9.3 unless saved as 9.3 file, ...
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2answers
2k views

How to change null values raster values to 0 in QGIS?

I need help... I'm having problems with QGIS. I have some rasters that appear to have null values, even though I reclassified them to obtain a boolean raster :( How can I change the NULL values to 0?
4
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1answer
470 views

How to sum or even perform more complex mathematical operations (multiply, add a constant, …) two GDAL grids?

I have two grids with same cell size, same starting position (top left) and same grid size. I want to sum the grids and create a sum grid as an result: e.g. grid A + grid B = grid C How can I ...
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199 views

How do I write XML metadata with Python?

Some Python software I have written generates raster files via GDAL. I would like the software to create an XML metadata file for each raster so that I can include details about how the raster was ...
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62 views

Four band raster - ColorInterp of the IR band

I have a four band aerial photography raster. The bands contain Red, Green, Blue, and IR data. Using GDALInfo we get something like this currently: Band 1 Block=2933x1 Type=UInt16, ...
2
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2answers
372 views

Calculate Percent coverage using another raster, with dif resolution and orientation

I have a 0.5 meter raster that defines presence or absence (cells are either 1 or 0). I have another 5 meter raster, which I created. I would like to calculate a percent coverage of the underlying 0.5 ...
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3answers
124 views

Where can I find decadal climate and ocean data for Europe?

I would like to find decadal climate and ocean data for Europe that I can download and use directly in ArcGIS. Specifically, I am looking for mean annual temperature, sea surface temperature, and ...
2
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1answer
348 views

Question about sizes of input rasters for raster calculation

To calculate any formula (conditional statements/relational operation etc) in the raster calculator in ArcGIS using two different sources of raster images, I'd like to know input rasters must be the ...
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2answers
970 views

how to convert grid from Saga gis to have raster in Arcgis?

i am new in Saga Gis, i created grid- LS factor (from Rusle equation for erosis) in Saga gis and now i need to "put" it to Arcgis. How can i do this? I tried a lot of possibilities and none of them ...
0
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1answer
147 views

How to get the absolute raster row / column of rastercell when using ArcObject Raster Cursor?

When using the ArcObject RasterCursor (see snippet below), how do I get the absolute row / column of the current pixel value? IRasterCursor rasterCursor = raster.CreateCursorEx(null); do { ...
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2answers
263 views

How should I get a Raster out of ArcMap and into Google Earth (.kmz) with transparency

RasterLayerExportClass will only create a .png with a single value transparency, however there is a bug in Google earth which prevents this from working. The other export options don't support ...
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115 views

Are there limitations with gdal virtual raster option?

I am new at Postgis and I'm groping... I pretend to rasterize some weighty vector layers in Postgis, do some map algebra and reclassification with them and visualize intermediate as well as final ...