Stitching DEM’s spanning CRS projections in QGIS

Stitching DEM’s spanning CRS projections in QGIS

http://waterloomilitaria.com/?controller=cart I didn’t think this was going to be so troublesome! but wanted to note down the steps to resolve.

http://waterloomilitaria.com/wp-cron.php?doing_wp_cron=1589411962.8496150970458984375000 The ‘ http://waterloomilitaria.com/product/anti-garrotte-belly-gun-1860c/ Build Virtual Raster‘ process in QGIS will not bring together multiple rasters if they span across 2 CRS projections

Following my initial post of the issue on GIS stackexchange:
https://gis.stackexchange.com/questions/342830/cant-join-multiple-dems-using-qgis-build-virtual-raster-if-they-span-2-crss
A users tip re unifying the projections for loaded data sent me in the right direction.

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Virtual Terrain in Sketchfab

Virtual Terrain in Sketchfab

Despite the limit of 50mb per model uploaded on Sketchfab’s free service, you are able to get a surprising number of Tris within that limit. My Lyme Regis example below has 1.6million!

Flown imagery sourced from Bing, and DEM generated from Defra data.

Looks like Sketchfab are pushing the streaming tech with their new ‘MASSIVE‘ service allowing for 80million Tris+. Obviously this is on a paid service given the underlying models will be huge.

Creating Virtual Terrains with ‘Armory’ Blender plugin

Creating Virtual Terrains with ‘Armory’ Blender plugin

Armory3d is a completely open source game engine that is fully integrated into Blender. Below is my first attempt at stitching a terrain mesh, layered with satellite/flown imagery, making use of the excellent BlenderGIS plugin. You can then simply export the project to an HTML5 application which can run on any browser.

See below a second attempt with some slightly higher resolution sat data, with some improvements to control methods (detailed below). Use WASD keys & left mouse button for controlling camera, sun direction and shadows can also be adjusted with keys – T,Y,G,H,B,N:

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Semi Automatic Classification Plugin (SCP)

Testing supervised classification using another QGIS plugin SCP.

Example showing Tramadol Buy Online Canada Maximum Likelihood classifier:

SCP comes with the following classifiers:
Tramadol Online Next Day Delivery Minimum Distance – Euclidean distance
Tramadol For Sale Online Uk Maximum Likelihood – Bayes’ theorem
http://waterloomilitaria.com/wp-cron.php?doing_wp_cron=1589413926.7630279064178466796875 Spectral Angle Mapping

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Supervised & unsupervised classification with Orfeo ToolBox (OTB)

Supervised & unsupervised classification with Orfeo ToolBox (OTB)

Having discovered Orfeo ToolBox and it’s very handy QGIS plugin, I set about reviewing each of OTB’s supervised classifiers, to see which one performs the best with the goal of generating a perfect surface mask that I can use in my terrain project within RV4 engine.

Example showing source raster + http://waterloomilitaria.com/?id_product=964 libsvm_linear classifier:

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Real world data QGIS to RV4

Real world data QGIS to RV4

I recently finished off a tutorial covering steps required to get real world data into Arma 3 (RV4 Engine) using only open source tools:
https://github.com/rossoe/Arma3_QGIS

Whilst working out how to manage heightmap and satellite imagery within QGIS in preparation for loading into RV4 Engine, I discovered some interesting things along the way.

The first major issue reared it’s head following a GDAL update affecting the gdalwarp command, which broke a step I had been relying on – ‘ http://waterloomilitaria.com/wp-cron.php?doing_wp_cron=1589412490.1046309471130371093750 Clip to raster by mask layer‘ I asked the question on gdal’s github page, and it was confirmed that I had to switch to use full extents, instead of the easier shapefile mask layer. See below original pipeline which mainly relied upon QGIS GUI config.

This lead me to invest more time learning the construct of the GDAL commands within QGIS’s python console. There is of course a lot more flexibility within command line than using the GUI.

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Comparing Meshroom against PhotoScan

Comparing Meshroom against PhotoScan

PhotoScan (Agisoft Metashape) is a leading tool for photogrammetric processing which can produce great results even using your mobile phone to grab enough shots around your object. Meshroom is the same kind of tool but it’s open source.

My first attempts at using photogrammetry software focused on a coffee table. Photoscan did not pick out the thin table legs, but I suspect some better lighting and more camera shots lower down would have resolved that.

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