Tag: FOSS

Database, Database Optimization, PostGIS, SQL

Contour data and table management in PostGIS

My contour dataset is almost ready to go live.  Just a few more tweaks.  I was manipulating it in the public schema.  I really want it in my base map schema “base”. Want to change schemas on a table in Postgre? No problem: ALTER TABLE public.cuy_contours_2_clip SET SCHEMA base; Rename a table? No problem: ALTER TABLE base.cuy_contours_2_clip RENAME TO base.cuy_contours_2; Save space by not storing … Continue reading Contour data and table management in PostGIS

Unknown's avatarsmathermather1 Comment
Database, Database Optimization, PostGIS, SQL

PostGIS and LiDAR– oops!

I won’t offer much prelude.  Read this post, and this post first… . Inadvertently I demonstrated the value of spatial indices, i.e. I meant to use them and didn’t.  In attempting to sort my tables by their spatial index I got the following errors: ALTER TABLE lidar_ground CLUSTER ON lidar_ground_the_geom_idx; ERROR:  “lidar_ground_the_geom_idx” is not an index for table “lidar_ground” ALTER TABLE lidar_veg CLUSTER ON lidar_veg_the_geom_idx; … Continue reading PostGIS and LiDAR– oops!

Unknown's avatarsmathermatherLeave a comment
Database, Database Optimization, PostGIS, SQL

Rethinking PostGIS Analyses– Remembering to CLUSTER

Something’s been nagging at me as far as the level of optimization (or lack there-of) that I did to my database before my other posts of using PostGIS to analyze LiDAR data (e.g. this post).  It seemed my results were remarkably slow, but I couldn’t put my finger on why that was problematic. Then, as I was testing a smaller lidar dataset in order to … Continue reading Rethinking PostGIS Analyses– Remembering to CLUSTER

Unknown's avatarsmathermatherLeave a comment
Database, Database Optimization, PostGIS, SQL

PostGIS and LiDAR, the saga continues

I ran these tests a while back, but I’m just getting to post them now.  These were run on a late model MacBook Pro, with a 2.4GHz Intel Core 2 Duo, with a couple of gigs of RAM on PostgreSQL.  In Postgre, if I run SELECT version(); I get: PostgreSQL 8.4.1 on i386-apple-darwin10.0.0, compiled by GCC i686-apple-darwin10-gcc-4.0.1 (GCC) 4.0.1 (Apple Inc. build 5493), 64-bit My … Continue reading PostGIS and LiDAR, the saga continues

Unknown's avatarsmathermather4 Comments
GDAL

Mapping places unknown– free global datasets and FOSS GIS are a great combo

I wanted to put together a quick and dirty map of a biological reserve in Ecuador, sort of a laptop exploration of a place quite distant.  At first, I thought I’d use Shuttle Radar Topography Misssion data to get the elevation information.  Then I discovered the ASTER Global DEM which is 30m resolution for the whole world.  Wow.  Cool cool data. (I used the Japanese … Continue reading Mapping places unknown– free global datasets and FOSS GIS are a great combo

Unknown's avatarsmathermatherLeave a comment
Database, PostGIS, SQL

Clipping Data

I loaded a set of contours into the database that are really nice, up-to-date LiDAR and breakline derived contours.  The are engineering grade aerial contours, but they are a very big and complex dataset.  So I’ve done what I had hoped was the hard part, using shp2pgsql, I’ve converted them to PostGIS insert statements and dumped them into the database only to find that some … Continue reading Clipping Data

Unknown's avatarsmathermather2 Comments
POV-Ray, Viewshed

Viewshed Analyses in Povray– Final Image

I completed this project a long time ago and have not blogged on it in over a year.  None-the-less, I realized that I hadn’t posted any final images for the viewshed analysis with Povray. So here is the summer viewshed analysis.  This is rendered with about (I think) 150,000 trees, each with 100,000+ leaves.  The cell tower here is in red.  The landscape colored in … Continue reading Viewshed Analyses in Povray– Final Image

Unknown's avatarsmathermather1 Comment
Other

IMCORR– using image correlation to georeference an image

IMCORR is a package distributed by the National Snow and Ice Data Center (did you know we have one of those?), or NSIDC, that performs image cross correlation between two images using a comparison between a moving image chip in each image.  It measures the displacement (in pixels) between the objects found in the two images, and writes that out to a text file.  It … Continue reading IMCORR– using image correlation to georeference an image

Unknown's avatarsmathermather1 Comment