Tag: FOSS

Database, Database Optimization, LiDAR Shootout, PostGIS, SQL

Dialog– What qualifies as a benchmark? Part 1

Normally, my blog is a bit of a monologue.  It’s not a bad thing, but can be a little lonely.  Every now and then I get a great (and often doubtful) comments, which enhances things considerably. What follows is some dialog about the LiDAR shootout series, largely between Etienne and Pierre, posted with their permission: Pierre: “Etienne, Stephen, “I really appreciate the benchmark work you … Continue reading Dialog– What qualifies as a benchmark? Part 1

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Database, Database Optimization, LiDAR Shootout, PostGIS, SQL

LiDAR Shootout! — New Chart, Final Results

In reviewing the final numbers and charts from Etienne and Pierre, above are the results we see.  The only revision is a moderate increase in speed for the PG Raster query. Final results in speed for lastools– ~350,000 points per second.  In other words– off-the-charts fast.  And the initial RMSE of ~25 feet was a mistake– it is probably closer to 0.2 feet. Stay tuned … Continue reading LiDAR Shootout! — New Chart, Final Results

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Database, Database Optimization, LiDAR Shootout, PostGIS, SQL

LiDAR Shootout!

For a couple of months now I’ve been corresponding with Etienne Racine and Pierre Racine out of Montreal Laval University in Quebec City.  They decided to take on the problem of finding the speed and accuracy of a number of different techniques for extracting canopy height from LiDAR data.  They have been kind enough to allow me to post the results here.  This will be … Continue reading LiDAR Shootout!

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Database, Database Optimization, GeoServer, PostGIS

Contours– Symbolized from a single table

In a previous post, I restructured the contour data for display in GeoServer, e.g.: UPDATE base.contours_2 SET div_10 = CAST( contours_2.elevation % 10 AS BOOLEAN ), div_20 = CAST( contours_2.elevation % 20 AS BOOLEAN ), div_50 = CAST( contours_2.elevation % 50 AS BOOLEAN ), div_100 = CAST( contours_2.elevation % 100 AS BOOLEAN ), div_250 = CAST( contours_2.elevation % 250 AS BOOLEAN ); The SLD styling … Continue reading Contours– Symbolized from a single table

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Ecology, Image Processing, ImageMagick, Landscape Position, POV-Ray

Landscape Position Continued– absolutely relative position calculation

I apologize in advance– this first post will be heavy on code, short on explanation. Landscape position, e.g. previous posts, can be trivial to calculate, but to make the calculations scalable to a large area, some batching is necessary. In this case, instead of a McNab index, we’re calculating the traditional GIS landscape position. Enter my favorite non-geographic tool, PovRay… . To the difference between, … Continue reading Landscape Position Continued– absolutely relative position calculation

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GeoServer, GeoWebCache

WMS vs. WMTS and GetFeatureInfo Requests

How to get GetFeatureInfo requests to perform against GeoWebCache?  Just don’t.  I’m unclear as to whether it is problematic to do this because of a known bug or known implementation differences between the (unofficial) WMTS standard as implemented by OpenLayers and GeoServer, but in Googling for answers to how to perform a GetFeatureInfo request against GeoWebCache, I discovered a workaround (logged here for example).  The … Continue reading WMS vs. WMTS and GetFeatureInfo Requests

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GeoServer, GeoWebCache

GeoWebCache Configuration

I’ve long delayed the configuration of GeoWebCache (GWC).  Automatic configuration within GeoServer’s deployment of it has been adequate until now.   Until now that I want to deploy tiles in something other than Google Mercator… . I’ve developed a cache setup for Ohio State Plane North, Feet (epsg:3734).  At first it was a going to be a cache just for our service area, then I thought … Continue reading GeoWebCache Configuration

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Database, PostGIS, SQL

Multi-Ring Buffers in PostGIS– Prep for Landuse Analysis

If we want to understand the factors affecting the quality of an ecological resource, adjacency is important. Adjacent land use and the fossil fuel inputs relative to keeping a land use in its current use seem to have strong correlation with, e.g. wetland quality.  I’ll have a deeper post on this with some citations, but this relatively simple process of analysis is called Landscape Development … Continue reading Multi-Ring Buffers in PostGIS– Prep for Landuse Analysis

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Database, Database Optimization, GeoServer, PostGIS, SQL

Contours– Structuring PostGIS data for viewing with GeoServer

Naively structured data is my bane– the desire (and need) to get stuff done so often overtakes the time needed to do things the better way. So, we bootstrap. A long time ago, we managed to load in a few tens of gigs of contour data into PostGIS, partitioned it into 2ft, 10ft, 20ft, 50ft, 100ft and 250ft tables using select queries with a modulus … Continue reading Contours– Structuring PostGIS data for viewing with GeoServer

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