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1500 questions
16
votes
2 answers
completing satellite imagery tiles when data coverage is less than 100%
I want to join several images (>=2) into one "best" image. Best is defined on low cloud cover and high data coverage. An example using free Sentinel satelite data follows.
See…
val
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16
votes
3 answers
Which remote sensing satellite is best used for vegetation extent mapping
I'm currently writing an assignment for my remote sensing class and while I think I have correct answer was wondering what people who do this stuff for a living think.
The question is: which satellite out the Landsat TM (Thematic Mapper) and SPOT 5…
Nathan W
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16
votes
2 answers
Creating "Inner Buffer" using ArcGIS for Desktop?
I am currently searching for how to create an "Inner Buffer" in ArcGIS for Desktop?
I have a lot of polygons (houses) in one feature class, and one big polygon (in another feature class).
I want so select all houses contained in that one big…
ChristianFu
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16
votes
1 answer
How to label geojson points in Leaflet?
How to show labels for geojson points in a Leaflet map?
There is Leaflet.label that is now deprecated in favour of L.Tooltip, but that only shows text on hover. I want to show the text labels directly on the map without needing user…
matt wilkie
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16
votes
1 answer
how to take cell size from raster using python or GDAL or RASTERIO
How to take cell size per X,Y using simple python or GDAL or RASTERIO?
and hot to count how many pixels have my raster with some packages..
I have find some code but is pyqgis and I don't need this package :
ras =…
Chris Papas
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16
votes
1 answer
Working with NaN/null and different extents in QGIS Raster calculator?
When it comes to NULL value and different extents of rasters I find it extremely cumbersome to use QGIS raster calculator. As far as I am aware there is no way to operate with NaN/Null value. So no matter what you do NaN/NULL in any input become…
Miro
- 9,744
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16
votes
1 answer
Difference between bounding box, envelope, extent, bounds?
Every time when I create a script to manipulate vector (point, line and polygon) in python I meet this doubt.
What is the difference between bounding box (bbox), envelope, extent, bounds?
Diogo Caribé
- 1,960
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16
votes
1 answer
Using some 'temporary variables' in QGIS Geometry generator symbol layer type expression?
Making use of the Geometry generator symbol layer type, I draw rectangles of dimensions @nv_bg_w (width) and @nv_bg_h (height) (project variables) to line features, either at coordinates text_x, text_y (attributes, if not NULL) or alternatively at…
Jochen Schwarze
- 14,605
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16
votes
3 answers
Distinction between pixel-based and object based classification?
I am struggling to clearly understand the distinction between pixel-based and object-based classification in the remote sensing domain and am hoping someone from this community can provide insight.
Based on the information I have so far, my current…
RDG
- 163
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- 1
- 5
16
votes
2 answers
Showing transparency slider by default in Layers Panel of QGIS
Is it possible to have a transparency slider shown by default in the Layer window, i.e. directly after adding a new layer, instead of having it to enable for each layer manually via layer-properties?
Matty
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- 5
16
votes
6 answers
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 do it but that is much too slow (convert raster…
stn
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16
votes
1 answer
Splitting Polygons at midpoint using ArcPy?
I'm attempting to split around 4000 polygons at their midpoint, perpendicular to their longest axis (ie across the width at the midpoint), as in the diagram below.
Ideally, I'd like to do this automatically and avoid manually splitting each…
Matt
- 171
- 4
16
votes
2 answers
Merging all tiles from one directory using GDAL
I would like to use GDAL (under Windows; OSGeo4W Shell) to merge all GeoTIFFs from one directory into a new GeoTIFF. I have tried to address them by writing c:\data\....\*.tif which however does not seem to work, using the Windows environment.
I am…
Arne
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16
votes
1 answer
Create a circle of defined radius around a point and then find the overlapping area on a shapefile
My use case is related to calculating the area of a polygon in a shapefile that is covered by another polygon.
Specifically, I want to do the following:
Create circles that have a 100m radius, from a data.frame of long/lat points
Overlay these…
Nick Tierney
- 163
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16
votes
2 answers
Creating Virtual Layer with PyQGIS
Is it possible to create a Virtual Layer through a Python script?
For example, I have a layer 'road', and I would like to perform the SQL query:
SELECT *
FROM road
WHERE type = 'Expressway'
Will this be possible? Is there any example I can refer…
Cy T
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