The Zanzibar Mapping Initiative is the largest civilian drone mapping project in the world — an ambitious project to map the Zanzibar Archipelago using a whole host of eBee drones. The project is nearing completion of mapping Unguja, the larger of the two main islands. Because of the large area to be covered, ZMI required an approach to partition the data into manageable flight areas. … Continue reading ZMI — Zanzibar Mapping Initiative Level 1
I’ve been working on base cartography for the research area in Rwanda. Unlike here in Cleveland, we have some great topography to work with, so we can leverage that for basemaps. But, it’s such a beautiful landscape, I didn’t want to sell these hillshades short by doing a halfway job, so I’ve been diving deep. Background First, some legacy. I read three great blog posts … Continue reading Gorilla research in Musanze, Rwanda: Hillshades continued
Guest post from my colleague Patrick Lorch who wrote up what we did the other day in order to view a whole bunch of tiled images in a directory in QGIS (I did some mild editing to his posts. Mistakes are mine). The great thing about the approach is that is generalizeable to most tools that use GDAL for their raster API. This is part … Continue reading Efficient delivery of raster data part 4
Subdivision of geographic data is a panacea to problems you didn’t know you had. Maybe you deal with vector data, so you pre-tile your vector data to ship to the browser to render– you’re makin’ smaller data. Maybe you use cutting edge PostGIS so you apply ST_Subdivide to keep your data smaller than the database page size like Paul Ramsey describes here. Smaller’s better… . Or perhaps you … Continue reading (Whichever tiler you use) and efficient delivery of raster data (image pyramid layer) (update2)
Back in 2011 I wrote a post about GDAL, translating MrSID files and trimming off the artifacts so mosaics work. I’m revisiting some similar work this week and realized I had lost my copy of FWTools that can deal with MrSIDs. The Internet Archive came to the rescue. At some point LizardTech licensed a DLL that allowed for compilation compatible with FWTools licensing so we could … Continue reading GDAL tools of the trade: GDAL, MrSid, and nearblack revisited
More landscape position pictures — just showing riparianess. See also https://smathermather.wordpress.com/2014/11/22/landscape-position-using-gdal/ and https://smathermather.wordpress.com/2014/11/24/landscape-position-using-gdal-pt-2/ Map tiles by Stamen Design, under CC BY 3.0. Data by OpenStreetMap, under ODbL Continue reading Landscape Position using GDAL — PT 3
Just pretty pics today of estimated riparianess. If you prefer a bit of code, see previous post https://smathermather.wordpress.com/2014/11/22/landscape-position-using-gdal/ Continue reading Landscape Position using GDAL — PT 2
Hat tip again to Seth Fitzsimmons. I’ve been looking for a good, easy to use smoothing algorithm for rasters. Preferably something so easy, I don’t even need to write a little python, and so efficient I can run it on 30GB+ datasets and have it complete before I get distracted again by the next shiny project (a few hours). Seth’s solution? Downsample to a low … Continue reading Landscape Position using GDAL
Want to load your favorite tiles into QGIS? How about a plugin-free QGIS TMS tiles via GDAL: http://www.3liz.com/blog/rldhont/index.php?post/2012/07/17/OpenStreetMap-Tiles-in-QGIS Really awesome… . Needs but one change: epsg:900913 should be epsg:3857 or QGIS (GDAL?) throws an error. Presumably you could also define epsg:900913 in some config file, but barring that create an XML file as follows, and load as a raster in QGIS: Now I can use … Continue reading Plugin-free QGIS TMS tiles via GDAL
Every now and then I get the urge to define my own projection. Usually, I sit down for a while, hit my head on the wall, and the urge passes. For a few years I have worked with the Lake Erie and Allegheny Partnership for Biodiversity on various projects. Now we are getting deep into region-wide data collection, and so I decided to define an … Continue reading Custom projections using spatialreference.org and gdal
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