Introducing Crunchy Data Warehouse: A next-generation Postgres-native data warehouse. Crunchy Data Warehouse Learn more
Martin Davis
Martin Davis
The goal of is to provide easy and efficient access to PostGIS from web clients. To do this, it uses the emerging OGC API for Features ( OAPIF ) RESTful protocol. This is a natural fit for systems which need to query and communicate spatial data. The core OAPIF specification provides a basic framework for querying spatial datasets, but it has only limited capability to express filtering subsets of spatial tables. In particular, it only allows filtering on single attribute values, and it...
Read MorePaul Ramsey
Paul Ramsey
A community member on the postgis-users mailing list had a question recently: I have a table of elevation points, and I would like to figure out an elevation profile for a flightline running through those points. How? This question is a nice showcase of some of my favorite spatial tools with indexing, point to point distance queries on a sphere, and nearest neighbor queries. I thought it would make a great post. The original question author was nice enough to share his elevation data, so I c...
Read MorePaul Ramsey
Paul Ramsey
Last month, just under the wire for a 2021 release, the 3.2 version of PostGIS hit the streets! This new PostGIS also supports the latest 3.10 release of GEOS, which underpins a few of the new features. The extension uses the GDAL raster library for things like vectorizing rasters and rasterizing vectors (yes!). This release exposed a few more cool GDAL algorithms. • The new ST_InterpolateRaster function allows collections of measurement points to be interpolated into a continuous raster s...
Read MorePaul Ramsey
Paul Ramsey
One of the curious aspects of spatial indexes is that the nodes of the tree can overlap, because the objects being indexed themselves also overlap. That means that if you're searching an area in which two nodes overlap, you'll have to scan the contents of both nodes. For a trivial example above, that's not a big deal, but if an index has a lot of overlap, the extra work can add up to a measurable query time difference. The PostGIS spatial index is based on a R-tree structure, which naturally t...
Read MoreElizabeth Christensen
Elizabeth Christensen
Crunchy Data hosted the third annual PostGIS Day on November 18th.This was our second year with a virtual format and another year of record attendance! We had attendees from more than 99 countries. PostGIS is the most popular geospatial database in the world, with: • over 300 vector and raster functions • high performance analytical and transactional functionality • easy integration with all third-party mapping and data processing tools over 300 vector and raster functions high perform...
Read MoreKat Batuigas
Kat Batuigas
In my last post, I did a simple intro to foreign data wrappers in PostgreSQL . postgres_fdw is an extension available in Postgres core that allows you to issue queries against another Postgres database. It's just one of many foreign data wrappers that you can use in Postgres, so for today's post we'll look at another that works especially well with spatial data formats: ogr_fdw. I had also previously talked about some different ways to get spatial data into a Postgres/PostGIS database , but...
Read MorePaul Ramsey
Paul Ramsey
Raster data access from the spatial database is an important feature, and the coming release of PostGIS will make remote access more practical by allowing access to private cloud storage. Previous versions could access rasters in public buckets, which is fine for writing blog posts , but in the real world people frequently store their data in private buckets, so we clearly needed the ability to add security tokens to our raster access. Putting rasters in a database is not necessarily a good ide...
Read MorePaul Ramsey
Paul Ramsey
One theme of the 3.2 release is new analytical functionality in the raster module, and access to cloud-based rasters via the "out-db" option for rasters. Let's explore two new functions and exercise cloud raster support at the same time. Can you believe that there is a complete raster data set of all SRTM elevation data online, in cloud optimized GeoTIFF format? It's true, there is (and much more), at OpenTopography ! The SRTM data set is a collection of 14380 files, with a pixel size o...
Read MoreMartin Davis
Martin Davis
My colleague Kat Batuigas recently wrote about using the powerful open-source QGIS desktop GIS to import data into PostGIS from an ArcGIS Feature Service. This is a great first step toward moving your geospatial stack onto the performant, open source platform provided by PostGIS. And there's no need to stop there! Crunchy Data has developed a suite of spatial web services that work natively with PostGIS to expose your data to the web, using industry-standard protocols. These include: • p...
Read MorePaul Ramsey
Paul Ramsey
One of the less visible improvements coming in PostGIS 3.2 (via the GEOS 3.10 release) is a new algorithm for repairing invalid polygons and multipolygons. Algorithms like polygon intersection, union and difference rely on guarantees that the structure of inputs follows certain rules. We call geometries that follow those rules "valid" and those that do not "invalid". The rules are things like: • Polygon rings should not cross themselves • Polygon rings should not cross other rings • Multipol...
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