Questions tagged [spatial-index]
In a database, a mechanism for optimizing access to data based on the spatial column(s) of a data table.
209
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Same Spatial Query on nodes table gives different read time
I have created 2 databases.
First one has PGSnapshot Schema which looks like this.
On this I fire query
select id,ST_AsText(geom)
from nodes
where
ST_Intersects(geom , ST_GeomFromText('POLYGON ((-...
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0
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11
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Extending pyrtree to return input index of each matched bounding box
After some effort I finally got a working version (on Python 3.9) of pyrtree by merging a couple PRs onto my fork of the original repo. You can see the code here:
Lightly updated version of pyrtree
...
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2
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132
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Finding nearest polygon in PyQGIS using QgsSpatialIndex
I am trying to write a custom processing tool for QGIS which joins the nearest attributes with some conditions. Therefore I'd like to use a QgsSpatialIndex to increase performance. This works ...
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Get map to use function-based spatial index (ST_GEOMETRY)
SDE.ST_GEOMETRY — Oracle 18c — ArcMap/EGDB 10.7.1:
I have a view that returns the startpoint of lines as an ST_GEOMETRY column:
create or replace view bc_atn_startpoint_vw as (
select
objectid,
...
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GeoPandas spatial index - passing RTree parameters to index
I am quite familiar how to work with the Toblerity RTree library:
import fiona
import rtree
with fiona.open(input_path,'r') as source:
p = rtree.index.Property()
p.filename = "index....
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155
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Spatial indexes with RTree for polygons
I am trying to understand about how R-tree works for polygon data. In other words, polygon is a list of vertices (points), however, I am wondering how spatial index can recognize the order of points ...
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Set a spatial index on a set of rows (without table) in PostGIS
I got a giant geometry that I retrieve from an API and I break it into smaller pieces with ST_Subdivide.
Right after, I'm inserting it into a temporary table (which is indexed and only contains a ...
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Producing Shadow Indexes in Google Earth Engine using maximum values from a ImageCollection
I'm trying to generate a Shadow Index using the maximum values from a image composite (ImageCollection). Here is the link with the code:
https://code.earthengine.google.com/...
6
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1
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Actual PostGIS query execution time MUCH slower than expected
I've run into a performance problem from which I'm not sure how to move forward. I have a table with ~150M rows. And I have a query that in EXPLAIN has a cost of just cost=0.55..209.36, but in EXPLAIN ...
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The spatial index algorithm for vectors does not run - QGIS 3.22
I try to set a spatial index to my vector layers after getting an error on a mask I did but the algorithm does not run. Anyone did experience that? Does it have an impact on clipping if I don't step a ...
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Getting index of special pixel (x and y position) or transform lat/lon of pixel to index in Google Earth Engine
I am trying to find the index (x and y pixel position in an image) of a pixel (ex: the pixel with max DN value). however, it has been challenging for me.
My code is:
var geometry3 =
ee.Geometry....
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1
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1
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How to speed up PyQGIS code for finding intersection of features in the same layer
I an deleting one of the intersecting polygons from a vector layer using PyQGIS code mentioned below. It is too slow as I have many features in the layer. Is there a way to speed it up?
index= ...
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Adding multiple Image using Google Earth Engine
I want to make NDBI indices to a certain location. But when I run the code it can only show part of it
//####################### Import SHP #######################
var countries = Indonesia //Import ...
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How do I use spatial index to speed up a model?
I want to process data with a model in QGIS. It works fine, but the bigger the datasets get, the longer it takes. The reason is, I use GeoJSON layers and they don't have a spatial index. That is why I ...
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Optimized query to find nearby locations
I am working with the GeoNames database which has around 10 million rows of locations including longitude and latitude.
I have tested around 6 various nearby location queries including spatial indexes....
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Parallelization of rtree index
Is it possible to share rtree index in memory with multiple processes? I have succeeded to use rtree in multiprocessing environment with joblib, but the problem is that each process has its own copy ...
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1
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131
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Choosing appropriate index for PostGIS data
I have been reading this blog by Paul Ramsey, and considering my own data.
https://blog.crunchydata.com/blog/the-many-spatial-indexes-of-postgis
I have a regular grid covering an area of the world. ...
- 419
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0
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147
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Understanding Rasterio index coordinates
So I read in a .tif image with rasterio and what I get out when printing dataset.read(1)
is what I understood a coordinate system in the "red" band of the image.
The coordinate system is in ...
- 195
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2
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183
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Index‐Based Built‐up Index (IBI) no in the specified range
I'm trying to calculate Index‐Based Built‐up Index (IBI). This index has been mentioned in A new index for delineating built‐up land features in satellite imagery. As mentioned in the paper, the range ...
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(QGIS 3.20) Adding features while spatial index is created makes them disappear
I am encountering a weird behaviour in QGIS 3.20 on Windows.
Steps to reproduce:
Create an empty project
Create a SHP layer.
Add a few features.
Save the changes to disk
At this point everything is ...
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1
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146
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Is a spatial index on a ST_Transformed geometry simply ignored when the transformation has the same target CRS than CRS of the geometry?
I have such vanilla index on a PostGIS table:
CREATE INDEX polygons_gix
ON public.polygons
USING gist (geom);
Because of this:
If using more than one transformation, it is useful to have a ...
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3
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607
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Optimizing an intersection between a single massive multipolygon (WKT) and many features from PostGIS
Context
I have a massive MultiPolygon (~90'000 vertices, super complex, spreading over 60km², with lots of holes and parts) resulting of some Python computation. This MultiPolygon is coming as a WKT ...
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2
votes
1
answer
268
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How to use spatial indexes in SQL queries made on geopackages
I'm trying to learn how to write geopackage SQL queries so that the r tree index is used, but I can't seem to find any good information. I'm just trying to write a simple query in the qgis db manager ...
- 187
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1
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587
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PostGIS: Does re-creating a spatial index after inserts or updates affect performance?
Creating a spatial index on a geometry field is very important. The docs also state that you should perform a VACUUM ANALYZE after large update operations. But is it ever necessary to drop an existing ...
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442
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GEE- Calculating Burned Area Index for Sentinel 2 (Filipponi et al. 2018) but getting binary result than index range
I am trying to calculate BAIS2 index for sentinel-2 collection over a study area in Google Earth Engine. I tried to create a function using expression but end result is binary image rather than index ...
- 121
2
votes
1
answer
76
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Grab/Index the raster bands before and after a unique band for each pixel (depth-wise) in a raster stack
I'm working with a time series stack of 28 raster bands. Each band is an image for a specific date, spanning all of the year 2020, and they are stacked in order. The stack (change_point_raster) is in ...
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BRIN Index on PostGIS Geography
I have about 1.5 billion points in a geography column which represent topography.
I'll be retrieving all the points that are within a certain distance of a given long/lat. I was able to create a GIST ...
4
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1
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237
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Selecting features that intersect features of another polygon with spatial index
Based on the answer of @mgri here: https://gis.stackexchange.com/a/224954/164953 I tried to select the features of a multilines layer intersecting less or more than 2 features of a multipoints layer.
...
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1
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118
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PostgreSQL/PostGIS KNN query using <-> operator in ORDER BY clause not using index
I am trying to set up a KNN query using the <-> operator in the ORDER BY clause and the query planner does not appear to be using the spatial index as expected.
I am not using bleeding edge ...
2
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1
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303
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Creating indexes with PostGIS using all CPU cores
I have to run a whole bunch of GIST index creation, on some tables containing lots of records (scale of many countries, OSM data):
CREATE INDEX CONCURRENTLY IF NOT EXISTS osm_footways_gist ON ...
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41
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Creating Quadtree/Space Filling Curve Index atop GeoTiFF
I'm a complete beginner in GeoTiFF manipulation. I'd like to get some help in possible Java/Python/Scala project which performs spatial indexing (Quadtree, Space Filling Curves) atop given image(s). I ...
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2
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283
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PostGIS- slow spatial UPDATE queries on 50mil rows
PostgreSQL 11.8, AWS hosted RDS instance, SSD, 8GB RAM, 3.0 GHz Intel Scalable Processor. Plenty of storage space.
I'm finding running updates on a large table using spatial queries is taking a very ...
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1
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153
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Optimising PostGIS ST_DWithin across many tables for existence only
I have 13 tables containing MultiPolygons in the same projection (27700). I am trying to write an efficient query to get back a Boolean for:
Is one polygon in table A within X meters of any polygon in ...
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1
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132
views
Can the QGIS spatial index be used to evaluate points contained in multiple polygons of shapefile layers using PyQGis?
I want to use the spatial index of QGIS to improve the performance in the spatial query of multiple points in multiple polygons, both are shapefiles, but has not given me good results in execution ...
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0
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335
views
Using spatial indexes on point to polygon intersection query in SQL Server
I have a table (tab_point) with about 5 million points and another table with a few thousand polygons (tab_polyg). I need to find what points intersect with what polygon (to establish a count of ...
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1
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109
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ST_GEOMETRY: spatial column must appear immediately after spatial relationship function for spatial index to be used
The docs for SDE.ST_GEOMETRY have a blurb that says the following:
When are spatial indexes used with ST_Geometry?
...the spatial column must appear immediately after the
spatial relationship ...
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1
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150
views
What is name of dataset in GEE to estimate level of urbanization for each county (district) in a country /region?
I am epidemiologist, not remote sensing expert. I am interested to find association between disease incidence /reported cases with urbanization (hypothesis " more bigger cities , more incidence&...
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Postgresql POSTGIS not using index field while having GIST index on geometry field [duplicate]
I have around 2M rows on my PostgreSQL table with GIST index on geo_point field but while I try to use ST_Distance or ST_DWithin it is not using the index instead it is doing Parallel Seq
Indexed ...
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PostGIS: Speed up intersect by filtering first
I have a table with 20 million polygons where queries take some time (with an gist index on the geometries). I thought I could speed up the queries by first filtering on an additional id (selectivity: ...
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votes
1
answer
155
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Function-based spatial index: Use sdo_geometry() constructor instead of custom function?
I have an Oracle 18c table that has XY columns, but not a SHAPE column. I've created a query on the table that dynamically generates an sdo_geometry SHAPE column.
sdo_geometry(2001, 26917, ...
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Determining area size of grid (reference grid) in ArcMap [closed]
How do I determine the area size (square kilometres) of a customised reference grid in ArcMap 10.7?
I have tried Data Driven Pages and it is not working for me. The idea is to know the area size of ...
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2
answers
439
views
When not to create spatial index?
As I realized once again connected with this answer to Joining attributes by location using QGIS, creating a spatial index can result in huge performance improvements.
However, I was wondering why ...
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166
views
Spatial indexing of GeoTIFF images (Java Library)
I have a requirement to spatially index each pixel of GeoTIFF images and store them in a scalable database. I intend to perform this in the following manner.
Divide each GeoTIFF into smaller tile ...
- 141
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437
views
Spatial Index warning from Spatial Query
I'm trying a spatial query using QGIS version 3.10 using a buffer layer and a set of species records. I wish to know how many species records fall within the buffer. When I perform the spatial query ...
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109
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Improving PyQGIS distance matrix efficiency
I have written a custom processing tool, which I use within a large graphical model in QGIS. I am looking for a way to speed it up.
First step of this processing tool is to connect every point of one ...
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4
votes
1
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328
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PostGIS speed up query on 9 million row polygon table
Table bl_data 9 million+ polygon rows with GIST index and the index is clustered
create index ii3 on bl_data using gist(geom);
CLUSTER ii3 ON bl_data;
I have a query that finds records with the same ...
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votes
1
answer
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When to use GiST and when to use SP-GiST index?
I'm aware of the documentation for both of the indexes, but can't decide which one to use.
PostGIS documentation on these indexes
Example:
Let's say we have table data with the POINT attribute that ...
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183
views
Implement Rtree index to custom objects list
I'm trying to improve a spatial calculation, and I think the most efficient way is to add a spatial index, but I'm not sure how to do it.
In one hand I have a list of custom objects, with a geom ...
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0
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261
views
Why does PSQL ignore spatial index in "where NOT ST_Contains", but uses in "where ST_Contains"?
I'm creating a new table of trips in my PostgreSQL/PostGIS database, where trips are comprised of a series of individually identified points, based on where the points within each trip are. The idea ...
10
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1
answer
804
views
Determining which QGIS layer has spatial index
I would like to loop over all layers within a QGIS project and determine which layer don't have a spatial index and cause QGIS to slow down.
I tried the method hasSpatialIndex() but this always ...
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