Rasters are regular grids of values, usually stored in an image-like format.
5
votes
1answer
259 views
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
...
13
votes
3answers
193 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 ...
1
vote
2answers
72 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
votes
1answer
54 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
votes
1answer
42 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 ...
3
votes
3answers
206 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 ...
0
votes
0answers
38 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 ...
6
votes
3answers
2k views
How to calculate raster statistics for polygons?
how can I calculate sums, averages etc of raster-points (multi-band) per polygon of a vector-layer. I was told that this is called "zonal statistics". I tried that with QGIS first.
There is a way to ...
7
votes
1answer
191 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 ...
0
votes
0answers
23 views
Attempts in C++ to read only a window of a raster fails using RasterIO. Can Help?
Under C++: I can read a raster image just fine if I read the whole thing one line at a time using RasterIO. If I follow the documentation fr reading a window, however, I get error messages that make ...
3
votes
3answers
99 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 ...
0
votes
0answers
34 views
How to change integer labels into strings for a raster layer and publish it as a map service to retrieve its legend?
In ArcGIS Desktop 10.1, I've got a raster layer that uses an internal colormap to draw its symbology in the TOC. The result is an integer value for each color symbol classification. I can edit ...
10
votes
4answers
362 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 ...
0
votes
0answers
314 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 ...
0
votes
0answers
38 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
votes
1answer
26 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 ...
2
votes
0answers
25 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
vote
1answer
81 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 ...
3
votes
2answers
98 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)
1
vote
1answer
79 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 ...
1
vote
1answer
76 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 ...
1
vote
4answers
49 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 ...
2
votes
1answer
169 views
GDAL_translate: converting ESRI GRID to Geotiff in batch
The Challenge:
To batch convert 1000 rasters in ESRI Grid binary to Geotiff using either using a batch file or Python 2.7 without ArcGIS/Arcpy module.
The Tools:
Win7Pro, GDAL 1.9.2 (via OSGeo4W), ...
1
vote
0answers
57 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)
...
2
votes
1answer
66 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 ...
0
votes
0answers
41 views
R-raster versus ArcMap Bioclim clipped values differ?
I have a set of lat/long ccordinates for which I wanted to pull corresponding BioClim (1-19) values. I first used ArcMap, without interpolating, and came up with a set of data. I then used R's ...
2
votes
1answer
150 views
How to Calculate Utilization Distribution Overlap Index (UDOI) in ArcGIS 10?
I was wondering if any of you happen to have any information on how to calculate the Utilization Distribution Overlap Index (UDOI) in ArcGIS 10? If I understand it correctly the UDOI takes two kernel ...
2
votes
0answers
53 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 ...
1
vote
1answer
80 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 ...
1
vote
0answers
50 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 ...
1
vote
1answer
28 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 ##
...
2
votes
1answer
44 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 ...
1
vote
0answers
53 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.
...
1
vote
2answers
76 views
How can i make a polygon of cells of a raster
I have 100 rasters, each raster has the same cell size and extent and i want to make a polygon over of each cell. Can anyone help me doing this?
Thanks in advance.
1
vote
1answer
115 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 ...
0
votes
1answer
55 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 ...
0
votes
0answers
58 views
question on terrain analysis in qgis particularly slope from .5 m dem
Trying to create representative slopes from .5 dem. It seems to do a wonderful job with the stream bottoms and also with the general trends. It shows it to be steep where steep and flat where flat. ...
3
votes
2answers
261 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 ...
0
votes
2answers
83 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
votes
2answers
110 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
...
7
votes
5answers
5k views
Get boundary of raster image as polygon in ArcGIS 10
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 ...
5
votes
3answers
233 views
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
votes
1answer
134 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
votes
4answers
290 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 ...
0
votes
0answers
139 views
Figuring out Latitude and Longitude from XY Image [closed]
I'm having difficulty calculating the latitude and longitude values of an image that I am hosting inside of a div tag on my webpage. I can easily figure out the x,y (pixel) coordinates of the image ...
0
votes
1answer
57 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 = ...
7
votes
2answers
129 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
votes
1answer
88 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 ...
1
vote
0answers
121 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 ...
0
votes
1answer
44 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, ...
