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1500 questions
41
votes
3 answers

Enabling "Snapping" in QGIS while drawing polygons?

I tried to draw polygons in QGIS 1.7.0 and somehow I can't find or failed to find the "Snapping" option. I'm used to ArcGIS 10.0 where you have some snapping options, like placing points of polygons at points/edges/shapes/etc., see image below. Is…
q9f
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41
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5 answers

Writing numpy array to raster file

I'm new to GIS. I have some code that converts infrared images of Mars into thermal inertia maps, which are then stored as 2D numpy arrays. I've been saving these maps as hdf5 files but I'd really like to save them as raster images so that I can…
EddyTheB
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41
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3 answers

Using QGIS Processing algorithms from PyQGIS standalone scripts (outside of GUI)

I am writing a script which must work outside of QGIS GUI. I call some API functions from qgis.core but I would like to use the processing plugin. I am able to import processing with sys.path.append() but I cannot run any process. Moreover, all…
vidlb
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41
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4 answers

Select bounding box using postGIS?

I want to create a query to select all ways and their nodes that exist within a bounding box using postGIS. The bounding box shall includes all details as osmosis "--bounding-box" command will retrieves. Is there any way to do that?
uriel
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41
votes
1 answer

Defining new custom projections in QGIS?

I'm trying to define a projection in QGIS. I want to add North America Albers Equal Area Conic. From the spatialreference site I copied the proj4 line: +proj=aea +lat_1=20 +lat_2=60 +lat_0=40 +lon_0=-96 +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83…
djq
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41
votes
7 answers

Development of a plugin which depends on an external Python library

I'm developing a Python plugin, the target is integrating into QGIS the functionalities of a PyPI Python library called 'elevation'. Is there an OS independent way of installing external Python libraries and making them available to the Python…
Engineer-G
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41
votes
3 answers

Differences between triangulation and trilateration

Looking around I noticed that many people interchange the terms (triangulation and trilateration) for the same sense. What is the correct sense of Triangulation and what are the differences from Trilateration?
adev
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41
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2 answers

Joining (concat) list of similar dataframes in geopandas?

I have a list of dataframes, all of the same structure and all are polygons. How can I add them all together using geopandas?
Philipp_Kats
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41
votes
3 answers

Is it possible to look at the contents of Shapefile using Python without an ArcMap license?

I wondered if it is possible to look at the contents of a shapefile using Python without having and ArcMap license. The situation is that you can create shapefiles from many different applications, not only from ESRI software. I would like to…
Caitlin
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41
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6 answers

Migrating geodatabase data into PostGIS without Esri apps?

Can you tell me how I can load geodatabase data into PostGIS without having to install Esri apps? The solution I found online talked about using ArcGIS to convert GDB to SHP and then importing SHP to PostGIS.
Gerson Galang
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40
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12 answers

Exporting feature class into multiple feature classes based on field values using ArcGIS Desktop?

I have a feature class with over 2,000 features, and I need to make them all individual feature classes based on a field. Is there a way to do this?
Sophie
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40
votes
8 answers

Setting all pixels with value <= 0 to "nodata" in DEM raster using QGIS

I am using QGIS. I have a DEM raster with pixel values between about 3000 and -0.0003. I need to set all pixel with a value of 0 and smaler (<=0) to "nodata" (for later raster calculations and to reduce the filesize). It seems for me that this is a…
MartinMap
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40
votes
10 answers

Generating points that lie inside polygon using QGIS

I am using QGIS. I have polygon feature and want to be able to generate points inside it. I need this for one classification task. Generating random points until one is inside the polygon wouldn't work because it's really unpredictable the time it…
user2024
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40
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4 answers

Using directional shading on boundaries for cartographic effect in ArcGIS Desktop?

The attached screenshot of a National Geographic map shows some beautiful directional shading of boundaries. I'm trying to reproduce this sort of shading for a burn perimeter map, as I want to highlight features within the burn perimeter and not…
Aaron
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40
votes
5 answers

Writing Shapely geometries to shapefiles

Can someone demonstrate a simple way to write geometry data-structures from shapely into shapefiles? I am particularly interested in polygons with holes and linestrings. It would also be beneficial to stay away from ArcPy (so osgeo, pyshp, etc.…
terra_matics
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