Tag: FOSS

Analysis, Cartography, Database, PostGIS, PostgreSQL, SQL, Trail Curation, Trails

PostGIS Cartographic Effects– Cartoonify Nearly Coincident Lines

In my previous post, a long 24-hours ago, I proposed some automatic modification of line for cartographic reasons. I had some flaws in my code. The points were over-rotated by 45 degrees. Can you spot why? Tip: it’s a basic trigonometric mistake. Here’s the corrected code (though there may be a better way): An alternate approach is to only move those points that are too … Continue reading PostGIS Cartographic Effects– Cartoonify Nearly Coincident Lines

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Analysis, Cartography, Database, PostGIS, PostgreSQL, SQL, Trail Curation, Trails

PostGIS Cartographic Effects– Cartoonify Nearly Coincident Lines

I’m still working on this query, but I thought I’d post what I’ve done so far. My intent is to produce scale-dependent exaggeration of the distances between quasi-parallel lines. The reason for this is so that lines such as street lines which are nearly coincident at a particular viewing scale can be spread from each other, much in the same way great cartography lies a … Continue reading PostGIS Cartographic Effects– Cartoonify Nearly Coincident Lines

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GDAL

gdal_warp, cutlines, and cwhere– simple tip for use on Linux

Mini GDAL tip of the day: gdalwarp, especially in combination with gdal_merge, is a powerful tool for doing all sorts on nice aggregation (read: mosaic’ing) of spatial raster data.  Unfortunately, at least with a google search, there’s very little to be found on demonstrating the use of queries in conjunction with cutlines, probably because in general these queries are not difficult to figure out. In … Continue reading gdal_warp, cutlines, and cwhere– simple tip for use on Linux

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Analysis, Ecology, GDAL

GDAL Slopes– Local Hydrologic Slope vs. the Standard Approach

Open Source software is not, of course just about warm and fuzzies, great support, rapid development cycles, shared costs, etc., it’s also about getting your hands dirty with someone else’s code and implementing stuff more quickly and more intelligently because of it, and hopefully learning something in the process.  You don’t have to poke under the hood to drive the car, but sometimes it’s nice … Continue reading GDAL Slopes– Local Hydrologic Slope vs. the Standard Approach

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Analysis, Ecology, Landscape Position, Other, POV-Ray

Landscape Position: Conclusion? (part 2)

From earlier post: “I’ve managed to pilot most of a fast high resolution landscape position workflow with PovRay as my magic tool. The final steps I hope to pipe through PostGIS Raster. In the meantime a screenshot and description: blues are riparian, raw ocre, etc upland categories, grey is mostly flat lake plain and mid slopes, all derived from just a high res DEM input … Continue reading Landscape Position: Conclusion? (part 2)

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Database, GeoServer

Leaflet, GeoServer, and Open Source Software Ramblings

I posted this post about an apparent problem in rendering of GeoJSON in Leaflet, and now it’s fixed a week later.  Why gush now, when for a few years developers on the GeoServer board have been fixing bugs I’ve found (often by the next day)?  Well for one, I very rarely find bugs in GeoServer– I just think I do, document everything, send it on, … Continue reading Leaflet, GeoServer, and Open Source Software Ramblings

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Analysis, GDAL, Image Processing

gdal_calc.py– Raster Calculator using Numby Functions

gdal_calc is a python script that makes it easy to do band math and logical operations with gdal/numby. This ranges from basic arithemtic operations to logical functions. And while gdal_calc.py has been around since 2008, it is but is a recent and revelatory discovery for me. I had just today resigned myself to properly learning python so as to use the gdal bindings. But, my … Continue reading gdal_calc.py– Raster Calculator using Numby Functions

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Analysis, Ecology, Landscape Position, Other, POV-Ray

Landscape Position: Conclusion?

I’ve managed to pilot most of a fast high resolution landscape position workflow with PovRay as my magic tool. The final steps I hope to pipe through PostGIS Raster. In the meantime a screenshot and description: blues are riparian, raw ocre, etc upland categories, grey is mostly flat lake plain and mid slopes, all derived from just a high res DEM input (no hydro lines … Continue reading Landscape Position: Conclusion?

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GeoServer

Complex Symbolization in GeoServer or Compass Rose Mania– the GeoServer Version

At my place of employment, we have a vegetation survey program with enough potential plots to serve 50 years of data collection. The points are laid out in a Generalized Random Tessellation Stratified (GRTS) to maximize the statistical power of the analyses we do with them. Read more about GRTS. I dare you. Actually, it’s not so bad if you understand Quad-Trees and the like– … Continue reading Complex Symbolization in GeoServer or Compass Rose Mania– the GeoServer Version

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CartoDB, Database, Leaflet, PostGIS, PostgreSQL, SQL

CartoDB, Leaflet, and a little anti-generalization

CartoDB is one of two hosted (read: cloud) PostGIS database implementations.  It has a maps API, an SQL API, and is some fun to use.  The other hosted PostGIS implementation is SpacialDB which has a Restful API, but can also take SQL.  I just got my key for the free version of that, so hopefully I will be reviewing use of that in the future … Continue reading CartoDB, Leaflet, and a little anti-generalization

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