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

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399 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 ...
2
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0answers
50 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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0answers
64 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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1answer
1k 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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1answer
2k 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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2answers
436 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 ...
2
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3answers
756 views

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 ...
2
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1answer
209 views

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 ...
4
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1answer
225 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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1answer
106 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, ...
5
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1answer
1k 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. ...
2
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2answers
67 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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1answer
188 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 ...
2
votes
1answer
234 views

Kriging from raster with missing 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 ...
2
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2answers
161 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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1answer
74 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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0answers
62 views

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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0answers
68 views

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 ...
2
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2answers
213 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)?
2
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1answer
263 views

Preserve attribute table while using Extract by Mask in ArcGIS

When using the Extract by Mask function on a raster with several columns (beyond value and count) in the attribute table, the resulting raster does not have all the columns (it only has value and ...
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1answer
243 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?
2
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1answer
120 views

Is this a known issue in gaps between masked raster and spatial polygon in R with mask command?

This is my codes raster file: RAD polygon(shape): ws_sfc RAD.sub <- crop(RAD, extent(ws_sfc)) plot(RAD.sub) RAD.sub <- mask(RAD.sub, ws_sfc) plot(RAD.sub) plot(ws_sfc, add = TRUE) ...
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1answer
537 views

What's the reason for this Invalid Layer “Cannot open GDAL dataset …” error

When adding a rasterfile with QGIS python console there appears an error when the first letter of a rasterfile to be added is not written in capital letters. Why this behaviour? Example case1: ...
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1answer
110 views

removing spurious lines in raster before or after vector conversion?

I'm looking for a feature/function in either python opencv/ndimage/gdal/etc. or qgis/saga/grass that will help clean up a skeletonized image that I'd like to vectorize into a shapefile of ...
2
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1answer
149 views

Intersect shapefile with raster, then determine proportion of each raster value?

Using the arcpy module in Python, I want to find the proportion of each pixel value within the boundary of an overlaying polygon. (The polygon is in a shapefile.) For example, there are 10 possible ...
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1answer
69 views

Using ArcGIS Polygon to Raster tool does not divide resulting raster on cells?

I try to create raster composed of small (5x5 m) cells (pixels) from a polygon in ArcGIS-10. I created a polygon (as a single object), and use Feature to Raster Tool and Polygon to Raster tool (of ...
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0answers
86 views

TIMESAT input image requirement?

I tried to work on TIMESAT but always facing a problem. Here is the method I have used. Seems correct, but I get a warning at the end. I have created a NDVI file from ENVI 4.8 >> Transform >> NDVI ...
3
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0answers
182 views

How to calculate 90% confidence interval in a raster stack

I have a stack of grid files (23) in ASC format from a MODIS sensor and I need to calculate a 90% confidence interval, mean, min, etc, for each one in R, how can I do that? specially the interval. ...
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5answers
951 views

Raster diff: how to check if images have identical values?

Is there a means to check to see if any 2 given raster layers have identical content? We have a problem on our corporate shared storage volume: it's now so big that it takes over 3 days to conduct a ...
2
votes
3answers
827 views

How to increase raster extent by filling extent with no data using ArcGIS Desktop without Spatial Analyst?

I am using feature to raster to rasterize water polygons. It only makes a raster the extent of the features in the polygons, whereas I would like it to be the extent of another existing .tif image. ...
3
votes
1answer
230 views

Classified Images of RandomForest-Classification look clustered

I performed a RF-classification. I have 6 bands, ~250 trainingpoints in a shapefile, OOB estimate of error rate: 1.56% Picture of take trainingpoints added. My code: ...
2
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0answers
114 views

How to Interpolate very large datasets in QGIS?

I am working with a very large set of point data, (XYAttribute) which I wish to display as a raster. I've been using Interpolate, this is successful but very slow. I have other programmes that ...
2
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1answer
150 views

Processing RGB+NIR raster into RBG?

I have a Geoeye 1 satellite photo that's a 4-band multispectral B,G,R,NIR, 11 bit raster. Ultimately I want to publish this raster as a web service (using Mapserver). I opened up the raster in Qgis ...
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2answers
142 views

Aggregating rasters with GDAL

I have a set of files that have been mosaiced into a global VRT in a particular projection and resolution. However, I have a need to report statistics on a (say) one degree grid, where the reported ...
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1answer
96 views

Flow accumulation raster loading in QGIS 2.4.0 with null values (but flow direction loading ok!)

I have been tasked with creating an open-source hydrology dataset for a community group. To do this I have exported the flow direction and flow accumulation rasters from ArcMap as TIFF files and then ...
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71 views

IMG and geoTIFF raster extraction

everyone. I'm very new to GIS technologies. Somehow, i need to extract raster(RGB data) data from geoTIFF and IMG files. What is the fastest way doing it?
3
votes
2answers
286 views

Merging raster and vector not working

I have 1 vector layer (counties) and 1 raster layer (population density). I have tried merging these two, so that I can examine population density within a county, but I have had no luck. It just ...
2
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0answers
211 views

Using R to subtract the polygon area of one shp file from another

I'm looking to produce a map from two separate maps in R. My Maps files are as follows: ftp://ftp.cpc.ncep.noaa.gov/GIS/us_tempprcpfcst/610prcp_20140822.zip #Map1 ...
4
votes
1answer
145 views

How to model a geodesic grid in PostGIS?

Abstract I've decided to use PostGIS for a hobby game project. It requires a lot of units allocated on the surface of a planet. I'd like to model not only the units (simple points), but also their ...
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2answers
778 views

How to produce “SpatialPixelsDataFrame” from stacked RasterLayer?

How to produce "SpatialPixelsDataFrame" from staccked RasterLayer ? I have a stacked rasterlayer and I want to convert them to SpatialPixelsDataFrame. RasterLayer information is > RAD.all[[1]] ...
4
votes
2answers
501 views

How to access raster NoData value?

I am trying to programmatically access the NoData value in a raster dataset as shown in the screenshot. Two tools that come to mind to describe raster properties do not seem to be able to describe ...
3
votes
1answer
234 views

Reading raster datasets from file geodatabase with FME?

I have a file geodatabase (10.2) with geodatabase feature classes as well as geodatabase raster datasets. I am using the Esri Geodb API reader in FME Desktop 2014 to read feature types from this ...
2
votes
2answers
462 views

Reprojecting Natural Earth raster into natearth projection with gdalwarp causing black squares?

I'm trying to reproject the Natural Earth 2 raster layer (http://www.naturalearthdata.com/downloads/10m-raster-data/10m-natural-earth-2/) into the natural earth projection ...
0
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0answers
116 views

Ortho-rectification of Aerial Image

I took an aerial image of our farm using RC quadcopter. How am I going to orthorectify this image? Please can you help me with detailed instructions/methods involving the process.
2
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1answer
209 views

Rasterizing Contours - How to remove 0 values

I want to convert vector contours to a DEM. From other posts, I wanted to utilise the Grass r.surf.contours tool. Initially I converted the vector contour layer to a rasterized contours using the ...
2
votes
1answer
952 views

How to assign CRS to RasterLayer in R

I have a layer with coord. ref. : NA. How can I assign coord. ref. : +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 to coord. ref. : NA? class : RasterLayer dimensions : ...
0
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1answer
575 views

I don't find the mistake in my RandomForest-classification

I am trying to make a RF-classification of aerial-imagery to specify tree-species. I extracted 3 bands and made a .csv file with columns: band1 band2 band3 x y class The band columns include ...
2
votes
1answer
179 views

Map algebra from files in multiple directories

I'm a rookie in python programming. I want to do map algebra for multiple rasters but these rasters are in different folders. Here's the code ive created so far: #Importing modules import arcpy from ...
2
votes
2answers
158 views

How to add updated tiles to ArcGIS mosaic

I have several hundred aerial imagery raster tiles (in ecw format) that I have loaded into a mosaic dataset. I would now like to 'replace' or 'overlay' an older aerial imagery layer with this dataset. ...
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0answers
82 views

Postgis Raster Unions Color Issues

Can someone explain to me what I am doing wrong here as I think I do not properly understand postgis raster bands. I have a set of geometries that I want to merge with a raster and created a raster ...