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

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452 views

How to fix “Raster layer: Provider is not valid” error when loading PostGIS rasters?

I compiled and installed the current QGIS master as usual and I imported some raster data into my postgres 9.3 database with postgis 2.0.2 extension. Whenever I try to import the raster data into qgis ...
3
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1answer
303 views

How to interpolate raster to get finer resolution?

I am working with precipitation raster layer. It happens the raster data to be in a resolution of 0.25 degrees grid. How could I interpolate those pixels to have a better resolution, say, a resolution ...
6
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2answers
89 views

How to calculate the difference between two rasters in QGIS?

I have two similar rasters of the Mount Vesuvius and surroundings: one spans 20 kilometers, and the other one 50 kilometers. The two rasters are overlapping: What I would like to do is to create a ...
2
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1answer
434 views

How to extract percentage of land cover from a raster according to multiple shapefiles?

I have a raster map that represents land cover of a region, and different shapefiles (total 120) in the same region. I want to know the percentage of every land cover for each shapefile. For example, ...
1
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1answer
20 views

How to work with Baccini et al.'s biomass map from ArcGIS?

Baccini et al. (2012) has produced one of the best biomass maps available for the world. One can find the map from one of ArcGIS repositories here. I downloaded the .pkinfo file for that map but I ...
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0answers
14 views

R Freezes when Plotting Spatial Data Frames

I have run into a problem where anytime I try and plot a Spatial DataFrame in R, the console freezes, regardless of the size of the file. I imagined this must be due to an issue with the path to one ...
0
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0answers
50 views

Call gdal_proximity() from R

I have a raster including eight land cover types (pixel values ranged from 1 to 8): > r class : RasterLayer dimensions : 9887, 30532, 301869884 (nrow, ncol, ncell) resolution : 10, 10 ...
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0answers
21 views

How to get all pixel values of raster within a GeoJSON FeatureCollection in PostGIS

I need to extract all pixel values in a raster within a GeoJSON mask, using ST_Intersects. Attempt (throws invalid GeoJson representation): select row_to_json(t) from (select * from table_name where ...
0
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0answers
14 views

How to calculate the world file [duplicate]

I have map image of size 2500x 2500 and i know the extent of the map image which is xmin=454651.17794, Ymin=2738724.37939,Xmax=550197.46330 and Ymax=2834270.66475. The Xmin and Ymin calculated from ...
3
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3answers
119 views

Statistics on classified raster overlaid with a polygon vector

I have a classified raster file and a polygon vector file. I need to overlay polygon and find out area occupied under each classification in each polygon. I am not familiar with R. Can you please ...
3
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1answer
68 views

Retrieve pixel value from raster layer in pyQGIS

I am trying to access the pixel data in all bands from a raster layer in QGIS from the Python Console. I have looked at several online resources including ...
1
vote
1answer
42 views

Building georeferenced GeoTIFF from mbtiles automatically?

I want a georeferenced raster.In that way I don't have to georeference this raster manually . I know that geotiff has the georeference inside it , I got the mbtiles of the map how do I build the ...
2
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0answers
53 views

Size of an object in raster image based on DPI resolution and number of pixels

I'm trying to estimate the size of an object in a raster image, with known DPI resolution. To evaluate the validity of this method, I do as follows: 1) I'm drawing a 0,02 in × 0,02 in black square ...
2
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1answer
54 views

Recommendation for getting TIF raster from modis HDF, for processing in R

I've downloaded a set of modis mod13q1 HDF files, e.g. MOD13Q1.A2016097.h11v05.006.2016114040325.hdf. I'd like to load the 250m_16_days_EVI and 250m_16_days_pixel_reliability bands into R as rasters. ...
2
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1answer
193 views

Why am I losing part of my raster when I reproject?

QGIS 2.0 Working with tiff raster file. Reprojections are in WGS84 Mercator. Here is my problem: I am trying to use buffers or urban areas to analyze light intensity on a raster layer. I want 30 ...
0
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1answer
197 views

Attribute table is missing in raster after using extract by mask tool

Every time I use the extract by mask tool, the rasters that are created don't have an attribute table (i.e it's greyed out). Does anyone know what is causing this and why these rasters essentially no ...
3
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1answer
51 views

Importing large .asc files into QGIS

I've been given two .asc files containing a 1m raster data from a LiDAR survey. I only have access to QGIS.2.14.1 (which I'am using for the 1st time only having previous experience with ArcGIS) and I ...
3
votes
1answer
171 views

Rasterize vector while adjusting extent and resolution to reference raster?

I have a vector file which I want to rasterize and adjust its resolution to the reference map, in QGIS. I tried spatial_sync_raster function in R to set all the rasters into the same resolution as ...
2
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0answers
19 views

How to generate random points from classified raster layer?

I need to generate random points using a raster layer, which is classified into 5 classes of TPI (terrain position index). This should be a stratified random sampling design, with an equal amount of ...
4
votes
2answers
94 views

Identifying individual pine trees without using LiDAR data?

Are there any ways to identify individual pine trees without the use of LiDAR data? Crown identification seems irrelevant. My goal is to do a rough treetop calculation to get an idea of how many ...
0
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1answer
247 views

What exact format do I need to have for the inputs to make Path Distance work?

I am trying to run the Path Distance tool in ArcGis 10.1. Ideally I would like to utilize Tobler's hiking formula anisotropic approach to slope and a land cover cost surface to calculate the least ...
0
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1answer
46 views

Creating raster image using Shapefile in ENVI?

I have shapefile containing polygon boundaries and want to change them as a raster image in ENVI 5.3. Although, this could easily be done in ArcMap or other GIS software, however, I will have to ...
0
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0answers
6 views

How do I display NAD 1927 Albers with other data?

I have some raster datasets which are in NAD 1927 Albers projection. I cannot seem to display any other type of data with this projection. I get the pop-up projection warning when trying to add a ...
5
votes
1answer
94 views

Krovak projection EPSG 5514: Correct data transfer between R and ArcGIS?

I have a problem which many ArcGIS, QGIS and R users from Czech Republic and Slovakia may encounter. In ArcGIS, I am working EPSG: 5514, Projected Coordinate System, defined as: ...
0
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1answer
215 views

using raster.predict for Cubist model, factor levels list

I would like to thank in advance any help or advice. Let me know if I need to provide more reproducible data/code. I am working on a Cubist prediction model for soil texture, using continuous and ...
2
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0answers
14 views

Issue loading PostGIS out-db rasters (either in QGIS or MapServer)

I'm playing with a few different options of storing raster data via PostGIS to visualize (eventually in a web app). The out-db or out-of-database storage seems the best option, but I can't seem to ...
0
votes
1answer
24 views

How to merge rasters with the same but unequal cell size in ArcMap?

I'm trying to merge raster tiles that all have the same, but unequal cell size (X: 2,8, Y: 2,9). When I use the Mosaic To New Raster tool, I can enter ONE cell size which either results in a raster ...
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0answers
23 views

Zonal Statistic Tool

In ArcGIS, I have a grid 5x5km (I have it both in vector and raster formats) I want to calculate, based on this grid, the zonal statistic (MEAN) of a raster 30x30m pixel size. The raster overlaps ...
0
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1answer
49 views

Exporting Raster from SAGA and importing it to QGIS - error CRS was unidentified

I make raster files from LiDAR las files in SAGA - CRS of .las is Slovenian national Grid. Then i export it as GeoTiff (Import/Export - GDAL/OGR - Export GeoTiff). When i import it into Qgis (Project ...
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0answers
22 views

Raster Precision QGIS

I am using r.patch extension in QGIS to join a number of LiDAR tiles, some of which overlap hence i am carrying out this task before utilising in a hydraulic model. R.Patch works fine, however the ...
1
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1answer
41 views

Generate ESRI grid with xllcenter/yllcenter in header

I'm trying to generate ARC/INFO ASCII GRID (*.asc) from point feature class using Create TIN - TIN to raster - Raster to ASCII functions. I'm looking for a way to have the output raster file header ...
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1answer
21 views

Raster to point

I have a raster (5km pixel side) and I want to create a shapefile of points, one point per pixel (like a centroid), each point carring the correspondent pixel value. I run "RasterToPoint"tool in ...
2
votes
1answer
40 views

How can I calculate the percent of a raster cell covered by a polygon?

First, I am going to try and intersect a raster and a polygon shapefile. I'm not 100% sure how to do this (or if I need to do this for the next step), so if you have any suggestions please let me ...
0
votes
1answer
291 views

Gridding a LiDAR point cloud? [duplicate]

I have been trying to grid a point cloud, version1.2, LiDAR datasets which are intended to be used for hydraulic simulation of flood propagation. Already, I have used Arc* to work on the traditional ...
13
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10answers
31k views

Get boundary of raster image as polygon in ArcGIS Desktop?

I have a rectangular raster image in ArcGIS. My question is: how can I produce a polygon which is just the extent of the raster image? That is, I want to have a polygon layer with a single ...
1
vote
1answer
43 views

Convert a raster with one band into a raster with RVB bands on QGIS?

So yesterday i downloaded a raster tile on a WMS server and exported it with Grass. I get a raster with 3 bands, i treat with the Semi automatic classification Plugin in QGIS and it works perfectly. ...
0
votes
2answers
339 views

Issues calculating range with QGIS 2.0 raster calculator

I would like to calculate a simple range using the QGIS 2.0 Raster Calculator, but am getting strange results. I believe I am not using the correct syntax. To get all values between .003-.5, I ...
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votes
1answer
306 views

Creating an R factor raster in RUSLE Soil Loss equation with multiple input rasters

I am attempting to obtain the rainfall erosivity "R" factor for the RUSLE Soil Loss equation using rainfall PRISM 30 year history data. I have both monthly and annual data that comes into ArcMap as ...
0
votes
1answer
22 views

How to extract single band from multi-band radiometry raster using R?

I am having trouble extracting single band from multiple multi-band raster. I have no problem doing it on single raster file. Is there a way to loop through all the raster images to extract a single ...
-1
votes
0answers
29 views

Calculating total area overlapping raster DEM color interval whose boundaries are confined by another vector? [duplicate]

Example: I tried running raster calculator on intersections then zonal statistics checking "count" and "sum" but I get a huge table of 8000+ rows and two columns, however each cell usually have a ...
5
votes
4answers
153 views

ArcGIS 10.3: Insert rotated image without background

How can I insert this image into an mxd so the white background doesn't show up? I've tried using photoshop to delete the background and save it as a format that supports transparent backgrounds (gif ...
3
votes
3answers
3k views

using Python to calculate NDVI, output as a Geotiff

I need a script that can calculate NDVI from two separate input Geotiff files, then output the results as a Geotiff. I wrote following script, most of which is borrowed from various on-line sources ...
-2
votes
1answer
24 views

“First” and “Last” from Global Forest Change [closed]

What are the "first" and "last" rasters provided by the Global Forest Change data set?
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0answers
24 views

Selecting cells with values from DEM those are above specific value corresponding to each polygon?

i have a shapefile with 2000 polygons and a DEM. i want to calculate zonal mean for each polygon considering values from DEM which are above a particular value for each polygon. i want to it with ...
0
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2answers
53 views

R: creating an error matrix from two rasters

I have two land use rasters (6 classes each) and I'd like to create an error matrix (errors of omission and commission) from them both. The premise is that I have a very fine 'base' raster and have ...
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vote
2answers
38 views

Can raster maps be stored in a SQL Server spatial database?

Can raster maps be stored in a SQL Server spatial database? And if so, how? ... I'm aware of VARBINARY and FILESTREAM for images, but can only see GEOMETRIC and GEOGRAPHY for vector data
0
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2answers
22 views

mapping with spplot

This question should be easy! I am using spplot for visualizing a map with suitable results. However, I would like to know how to set the limits of z, because the values are not being discriminated. ...
8
votes
1answer
287 views

Calculate mean value of polygon from raster in PostGIS

I started with a NetCDF .gri and .grd raster file of the UK provided by a colleague. I clipped it in R to be only London, exported and converted to a ASC file, and then imported it to PostGIS using ...
2
votes
0answers
19 views

Creating a reference raster in R

I need to create global reference raster (100km grid, Eckert IV). Later, I will project other various rasters (with different resolutions and projections) into the resolution/projection of the ...
1
vote
2answers
29 views

How to export vector file in GrassGIS to QGIS

I am using GrassGIS to analyze watershed. I created a stream vector extracted from raster elevation data, how to extract the stream vector file so I can open it using QGIS?