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--- arma3:terrain:qgis-real-world-data-tutorial [2019-02-11 02:57]
snakeman added new update from ross.
+++ arma3:terrain:qgis-real-world-data-tutorial [2022-01-04 05:59] (current)
snakeman opentopo 404 link and typos fixed.
@@ Line 7: / Line 7: @@
 The goal was to achieve an export satellite image and heightmap with the same or better quality than would be possible with Global Mapper.
-The is my second revision of this process as I recently discovered that due to an update to GDAL (**2.4.0**) one of the key steps in the original tutorial using '**Clip Raster by Mask Layer**' no longer works perfectly!
+I've used GDAL command lines where possible, which simplifies the process a little, and reduced additional processing on the data.
-So I reworked the process by getting a bit more under the hood, and using GDAL command line where possible, this also simplifies the process a little and reduced even further processing on the data.
+The following software versions were used for this tutorial:
-This tutorial used the following software:
 **[[https://qgis.org/en/site/forusers/download.html|QGIS v3.4.3]]**
@@ Line 54: / Line 52: @@
 ===== Heightmap: =====
+This tutorial covers single raster heightmap as per the kind you will find on [[https://portal.opentopography.org/raster?opentopoID=OTSRTM.082015.4326.1|opentopo]], I will detail steps for heightmaps spread across multiple rasters in another update. as they will require additional steps likely including Merge / Build Virtual Raster commands. This section does not cover any re scaling of heightmap, which I would recommend against anyway. Remember [[https://pmc.editing.wiki/doku.php?id=arma:terrain:grid_cell_size|Grid size x Cell size]] should = the same size (meters) as your source heightmap selection.
 **Drag and drop your heightmap '.asc' into QGIS**
-This tutorial covers single raster heightmap as per the kind you will find on opentopo [[http://opentopo.sdsc.edu/raster?opentopoID=OTSRTM.082015.4326.1|here]], I will detail steps for heightmaps spread across muliptle rasters in another update. as they will require additional steps likely including Merge / Build Virtual Raster commands.
+If you do use opentopo for source of Heightmap, make sure extract both the **.asc** and **.prj** files before proceeding with below. They should both be in the zip file from opentopo.
 **Set QGIS to appropriate CRS for location of your HM**
@@ Line 66: / Line 66: @@
 Select the CRS to match your real world data, in this example its ‘**WGS 84 UTM zone 20N**’ because the terrain is from the Montserrat in the Caribbean. See also [[https://pmc.editing.wiki/doku.php?id=arma3:terrain:utm-projection|UTM projection]].\\
-This will ensure your QGIS project space works appropriately with any other data you want to add - eg road shapefiles etc. Terrain Builder will only use UTM 31N but we'll get to that later.
+This will ensure your QGIS project space works appropriately with any other data you want to add - eg road shapefiles etc. Terrain Builder will only use **UTM 31N** but we'll get to that later.
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-13b.png}}
@@ Line 106: / Line 106: @@
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-AdvancedDigitizing.gif}}
-After the last **left mouse click** from the step above, the tool is still waiting to plot more points, so to finalise the square do a **right mouse click**
+After the last **left mouse click** from the step above, the tool is still waiting to plot more points, so to finalize the square do a **right mouse click**
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-20b.png}}
@@ Line 113: / Line 113: @@
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-21.png}}
+Save the above edits to the shapefile by clicking on the layer & selecting ‘**Toggle Editing**’
 **Obtain extents from square feature**
@@ Line 143: / Line 145: @@
 import os\\
-os.system(r%%'''%%gdalwarp -t_srs EPSG:**32620** -wo SOURCE_EXTRA=1000 -tr **5.0 5.0** -srcnodata "-9999" -r cubic -of GTiff -te **576787.687480 1841104.815839 597267.687480 1861584.815839 D:/Arma/Heightmaps/Opentopo/output_srtm.asc** **D:/Arma/QGIS/Montserrat/converted.tif**%%'''%%)
+os.system(r%%'''%%gdalwarp -t_srs EPSG:**32620** -wo SOURCE_EXTRA=1000 -tr **5.0 5.0** -srcnodata "-9999" -r cubic -ot Float32 -of GTiff -te **576787.687480 1841104.815839 597267.687480 1861584.815839 D:/Arma/Heightmaps/Opentopo/output_srtm.asc** **D:/Arma/QGIS/Montserrat/converted.tif**%%'''%%)
 Some explanation of the key parameters:
@@ Line 178: / Line 180: @@
 ==== For single tile export ====
-**Load in just the '.map' files generated from Terra incognita into QGIS**
+**Load in just the '.map' files generated from Terra Incognita into QGIS**
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-1b.png}}
@@ Line 289: / Line 291: @@
 And list them out for safe keeping -
-TL -  Extent: (576787.687480, 1851344.815839) - (587027.687480, 1861584.815839)\\
+**TL -  Extent**: (576787.687480, 1851344.815839) - (587027.687480, 1861584.815839)\\
-TR -  Extent: (587027.687480, 1851344.815839) - (597267.687480, 1861584.815839)\\
+**TR -  Extent**: (587027.687480, 1851344.815839) - (597267.687480, 1861584.815839)\\
-BL -  Extent: (576787.687480, 1841104.815839) - (587027.687480, 1851344.815839)\\
+**BL -  Extent**: (576787.687480, 1841104.815839) - (587027.687480, 1851344.815839)\\
-BR - Extent: (587027.687480, 1841104.815839) - (597267.687480, 1851344.815839)\\
+**BR - Extent**: (587027.687480, 1841104.815839) - (597267.687480, 1851344.815839)\\
 **Run GDAL command for each quarter to set cell size and CRS and clip to shapefile square extents**
@@ Line 302: / Line 304: @@
 ===== Loading your assets into Terrain Builder =====
+I would recommend saving copies of any files to be used in **Terrain Builder** into a separate terrain project folder. This will prevent your source project files being adversely affected, and potentially no longer working within **QGIS** - particularly relevant to those changes mentioned below.
 **Heightmap (.asc) edits**
-Open your **asc** in notepad and change the following to ensure it loads in Terrain builder:
+Open your **asc** in notepad and change the following to ensure it loads in **Terrain builder**:
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-14.png}}
@@ Line 311: / Line 314: @@
 Save to a new asc, whilst maintaining the original for use in your QGIS project space
-Before loading the asc file into Terrain Builder, delete the .prj file. Otherwise it will not import into TB.
+Before loading the asc file into **Terrain Builder**, delete the .prj file. Otherwise it will not import into TB.
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-09.png}}
@@ Line 318: / Line 321: @@
-Before loading the satellite image into Terrrain Builder delete the .bmp.aux file
+Before loading the satellite image into Terrain Builder delete the .bmp.aux file
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-08.png}}
@@ Line 336: / Line 339: @@
 ===== Preparing Road Shapefile =====
-**Load in road shapefile**
+**Load into QGIS (drag and drop) road shapefile**
+In this example I got a good dataset from - [[https://data.humdata.org/|https://data.humdata.org/]]
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-37.png}}
@@ Line 345: / Line 350: @@
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-38.png}}
-Save features from clip to new shapefile -  selecting correct **CRS UTM-20**\\
+Save features from clip to new shapefile -  selecting appropriate CRS, in this example **CRS UTM-20**\\
 Top Menu - **Layer** > **Save As**
@@ Line 461: / Line 466: @@
 {{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-56.png}}
+===== 3D Preview using Qgis2threejs =====
+If you want to see an instant 3d preview of your terrain within QGIS you can with the amazing plugin **Qgis2threejs**
+First install it:
+Top menu > **Plugins** > **Manage and Install Plugins**
+{{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-57.png}}
+RMB on the Merged layer and select **Zoom to Layer**
+Then select both the **Merged** raster, and the original source heightmap - deselect all other layers
+{{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-58.png}}
+Start the Qgis2threejs plugin - Top Menu > **Web** > **Qgis2threejs** > **Qgis2threejs Exporter**
+{{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-59.png}}
+Select source heightmap and nothing else
+RMB on heightmap > **Properties**
+Set the **Resampling** level to **6**
+Set **Resolution** to **400%**
+{{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-60.png}}
+Enjoy browsing around your terrain in 3D:
+{{https://pmc.editing.wiki/images/Ross-QGIS-Tutorial-61.png}}
+You can also export your terrain to a browser interface if you want - **File** > **Export to web**
-**Coming Soon:**
-  * Assisted image classification - for creation of mask
-  * 3d preview using Qgis2threejs

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