Questions tagged [vectorization]
The conversion of raster data (an array of cell values) to vector data (a series of points, lines, and polygons).
184
questions
1
vote
1
answer
119
views
Fastest way to clip millions of small polygons and storing results as JSON [closed]
I have a dataset with couple million farm polygons (around 2.5 million and only expected to grow in the future), and I need to calculate the NDVI for these farm polygons, with some basic stats (...
- 3,346
0
votes
1
answer
83
views
Convert a PNG file to a line layer in QGIS
I have a map in PNG-format that looks like this:
I have imported it into QGIS as a raster. I want to create a line layer as a network based on the blue and pink lines. Is there a way to create a line ...
- 85
0
votes
2
answers
75
views
Converting vectorization (raster to vector) with small steps in values in QGIS
I have a raster file that contains water depths in m. The water depths are the only attribute and should be transferred to the vector layer.
The raster files have a cell accuracy of 1m x 1m. I would ...
- 19
0
votes
0
answers
31
views
Extract a vector from a raster with a single boundary in QGIS
I have a "problem", I need transform a raster in a vector and it works but some pixels like the one in the print it is separated from the boundary, and for my use (a specific use of ...
- 91
0
votes
1
answer
40
views
ReducetoVectors in Google Earth Engine not working with the Mollweide transformation. Need to calculate zonal statistics for global scale analysis
My study is a global-scale analysis of the factors driving forest gain, with grid cells as the unit of analysis. I need to calculate the amount of forest gain per ~65km2 hexagonal grid cell at the ...
1
vote
1
answer
63
views
Generate points from raster image in QGIS
I'm hoping to generate a new vector file from select points from a raster image in QGIS. I don't know if it is possible.
For instance, I would like to generate a vector point file that puts a point ...
0
votes
0
answers
65
views
Convert topographic map to vector and text
I have a topographic map in TIFF format and I vectorized it in QGIS (3.22.0). For my project I needed the settlements, which I was able to extract. More importantly are the names of the settlement. ...
- 557
0
votes
1
answer
101
views
GEE Export individual FeatureCollections as shapefiles from an image Collection
I have run an NDWI index for an Image collection and thres holded the results, which I want to import as individual FeatureCollections (shapefiles).
My code is of course longer, but teh most importan ...
0
votes
1
answer
56
views
Differentiate vertical and horizontal shapes
I have the following shape file:
Each polygonal area (the lines are areas) is one feature in a single Shapefile.
Can anyone think of a simple method that can be implemented with qgis to separate the ...
- 140
0
votes
0
answers
143
views
How to convert raster to vector by generating center lines?
I need to vectorize the raster by keeping one center line trough the boundary pixels. My solution would need to be very similar to this question: Converting raster to vector by generating center lines?...
- 1
0
votes
1
answer
24
views
Abrupt error when trying to run model with viewshed as batch process
I am trying to run the following model as a batch process. In summary, I take a DEM raster layer and a number of individual points as separate .gpkg files in a directory (these points have been ...
- 783
1
vote
0
answers
113
views
Smoothing a vector layer in Google Earth Engine
I extract riverbanks out of Landsat images at Google Earth Engine. After the vectorization of my raster image I receive a shapefile of the riverbank with many unwanted vertices. How can I smooth the ...
- 11
0
votes
0
answers
47
views
Why r.to.vect process takes too much time with topology analysis?
My task is to vectorize a standard landuse map (PROBA-V discrete classification) for extent 118.747182 54.231218 124.946218 60.060467 degrees. Raster is too detailed for me, so I generalize it.
I use:...
3
votes
1
answer
148
views
Chain the output of gdal_polygonize to ogr2ogr
I am doing a two step process:
Polygonize a PNG raster via gdal_polygonize.py
Add a custom field named id
Upload the resulting vector to PostGIS via ogr2ogr
I am currently doing it in two steps, ...
- 91
4
votes
1
answer
634
views
Vectorizing all pixels as separate polygons using rasterio
I use rasterio.features.shapes and use the geometry of pixels in raster data to create polygons for each pixel. Pixels with the same value merge these pixels if they are adjacent.
What I want is for ...
- 73
0
votes
1
answer
271
views
QGIS .tiff to shapefiles by extracting colours
So I have the following raster file:
I would like to edit it so that I export all green, blue or purple areas as a single, new .tiff. Afterwards I would make a vectorization to be able to process the ...
- 140
1
vote
1
answer
476
views
What are strategies to simplify a vectorized raster layer?
For a GIS web viewer I am building, I plan to use large sets of vector data on coral reefs (source: Allen Coral Atlas). When viewing the downloaded data, it seems that the original source was raster ...
- 771
2
votes
1
answer
322
views
Create clipping masks using contour lines in QGIS
I'm new to QGIS and GIS in general. I'm trying to find a way to create height layers automatically and then use them to clip other layers.
In detail: Below is my area of interest. I have a raster ...
- 21
1
vote
0
answers
66
views
Visualization and vectorizing for AI in Google Earth Engine
I'm glad to find this space, I come from a background in economics and do not know the first thing about GIS (hope to learn as I go with this project).
I found an interesting dataset (https://...
0
votes
1
answer
406
views
Polygonize/Vectorize large raster
A raster(.tif) of 6.70GB needs to be converted into polygons. The raster is binary (0 & 1), currently I am using Polygonize (raster to vector) and its taking a considerable amount of time and the ...
- 615
7
votes
3
answers
361
views
Simplification by constrained anti-aliasing in PostGIS
I vectorized a raster data set, therefore, I'm facing a "steps" effect, or aliasing, due to the fact that the vectorization strictly follows the raster cells. So, the geometry is quite large ...
- 10.5k
2
votes
1
answer
2k
views
Extracting raster outline to a vector geometry
I have a raster data set with an irregular outline (every value outside is NaN) in Python (loaded from rasterio v.1.3a3 ):
I'd like to extract its outline to a vector shape, such as a Shapely ...
- 10.5k
1
vote
1
answer
130
views
Issues with vectorisation of thinned flow accumulation through r.to.vect on QGIS
I'm trying to produce a shapefile river network from a flow accumulation raster using the r.to.vect function and I've overcome some difficulties regarding bit depth and thinned raster.
n.b. I don't ...
- 339
0
votes
1
answer
763
views
How to transfer simple GeoTiff data into a database
I'm trying to turn a relatively simple GeoTIFF file into a dataset readable by an API.
End goal:
Build a GET method for an API like
/search_by_coordinates?lat=-73.1221&lng=44.4924 and get ...
8
votes
1
answer
614
views
Creating a seamless vector dataset from raster with gdal, R or Python
I'm trying to create a seamless vector dataset from an integer raster. "Seamless" as in: not gaps between features and no overlapping features.
The tools gdal_polygonize, pkpolygonize, terra:...
- 1,003
0
votes
0
answers
160
views
Converting Raster into Vector in QGIS
I am in process of converting one raster file ( JBA Flood score) into Vector file But due to raster size ( Possibly) process seems endless i.e. even after 9 hours process still continue. Is there any ...
- 103
0
votes
2
answers
601
views
How to polygonize NDVI raster using GDAL?
I have raster with NDVI values. I would like to polygonize the raster to get vector where each polygon is a pixel.
I have tried gdal.Polygonize as described in the documentation and that runs without ...
- 2,169
2
votes
0
answers
118
views
Contour Polygon Alternatives on QGIS
I am trying various ways to make polygons from raster data using 1 m DEMs. I am using QGIS 3.16 Hannover I have tried vectorizing my data, which does work OK, but I would like smoother boundary lines ...
- 545
0
votes
0
answers
107
views
Symbol recognition on a scanned image (map)
I have a specific task and I'm looking for possible approaches. What I'm trying to do is this:
I have a high resolution (600dpi) scanned, and georeferenced image of a map, and I need to be able to ...
4
votes
1
answer
888
views
Seeking GIS tool to automatically extract polygon geometries from images
Let's say I have multiple png images like the following one:
I'd like to find a way where I can automatically draw polygon geometries on this image. Something like the following:
My expectation is ...
- 1,163