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A little Gorilla Time
I miss my mountain gorilla friends in Rwanda. Let’s write a little more code to support them. I’ll be visiting Karisoke again next week, so it seems timely to post a little more code (HT Jean Pierre...
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Taking Slices from LiDAR data: Part IX
Part 9 of N… , see e.g. my previous post on the topic. We’ve been working to reduce the effect of overlapping samples on statistics we run on LiDAR data, and to do so, we’ve been using PDAL’s...
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Taking Slices from LiDAR data: Part VIII
Part 8 of N… , see e.g. my previous post on the topic. I didn’t think my explanation of sampling problems with LiDAR data in my previous post was adequate. Here are a couple more figures for...
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Taking Slices from LiDAR data: Part VII
Part 7 of N… , see e.g. my previous post on the topic. More work on taking LiDAR slices. This time, the blog post is all about data preparation. LiDAR data, in its raw form, often has scan line effects...
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Using foreign data wrapper to use PostGIS with SQLServer
Here was the problem that needed solved last week (we have a few similar problems in upcoming projects, so this was an exciting thing to try): we needed to use PostGIS to access data in a SQLServer...
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Taking Slices from LiDAR data: Part VI
I finally got PDAL properly compiled with Point Cloud Library (PCL) baked in. Word to the wise — CLANG is what the makers are using to compile. The PDAL crew were kind enough to revert the commit which...
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PostgreSQL table drop — a little fun with ouroboros
My latests posts on PDAL have been fun. For the moment, a quick bit of code for dropping all the tables in your PostgreSQL database. BTW, the following is a bad idea. Many bad ideas are really useful....
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Taking Slices from LiDAR data: Part V
For this post, let’s combine the work in the last 4 posts in order to get a single pipeline for doing the following: Calculate relative height of LiDAR data Slice that data into bands of heights Load...
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Yet another approach to ST_Buffer on geography
Another approach to ST_Buffer would be to subdivide the geometries before buffering, and put them all together at the end. ST_SubDivide can do this for us. We can tell it how may vertices we want in...
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ST_Buffer on Geography — Iteration
In my previous post, Imagico said: This is nice but still fails in one important aspect – it will create significant inaccuracies once your buffering distance reaches values where buffering in a single...
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Final?: ST_Buffer on Geography, or My love for @NullIsland
Thanks to Paul Norman’s reminder in a previous post, we now have all the pieces we need to complete an ST_Buffer function that exposes all the wonderful goodness of buffer style parameters to geography...
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ST_Buffer diving under the covers part 1
This will be a quick post. I just looked at how ST_Buffer is written in the PostGIS codebase, and I thought this was interesting. When you use ST_Buffer and specify geometry, buffer distance, and an...
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ST_Buffer for those who want really want all buffer features in geography
My previous post on improving buffering geography in PostGIS has three disadvantages: It doesn’t do this at a low enough level to automatically use the best available local coordinate system. This...
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ST_Buffer for those who want really round geographic circles
A little functionality request from @antoniolocandro on twitter: ST_buffer for geography has no option for quad_segs, alternative so buffer looks nice not jagged? cc @smathermather — Antonio Locandro...
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Normalizing tables in PostgreSQL: experiments with Fulcrum
Fulcrum by Spatial Networks is an interesting and very useful hosted service for collecting geo data in the field with whatever smartphone or tablet you already own. It works well, so long as you just...
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Editing in progress
Edit: Free book to the first to tell me what the is name of the children’s book on the armchair in the foreground: Book editing in progress… .
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Airspace — A deep rabbit hole
In previous maps we looked at Class B, C, and D airspace. Let’s add in Class E0 and E5… (not yet in 3D): (Map tiles by Stamen Design, under CC BY 3.0. Data by OpenStreetMap, under ODbL) Map showing...
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Airspace is complicated — and so I abuse PostGIS once again — Reprise…
In the previous post: http://smathermather.wordpress.com/2014/10/25/airspace-is-complicated-and-so-i-abuse-postgis-once-again/ we explore the 3D shape and complexity of controlled airspace. Now here’s...
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Airspace is complicated — and so I abuse PostGIS once again
Let’s ignore for a moment the drone hobbiest / enthusiast. What is the shape of airspace for airplanes and commercial and government unmanned aircraft flying under Certificates of Authorization, and...
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Drivetime analyses, pgRouting
We’ve got some quick and dirty pgRouting-based code up on github. I say quick and dirty because it directly references the table names in both of the functions. I hope to fix this in the future. The...
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