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Updated Creating shape files in QGIS for map data (markdown)

FinCenturion 2022-11-18 21:50:21 +02:00
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Creating-shape-files-in-QGIS-for-map-data.md

@ -34,10 +34,11 @@ Through PyDCS we already have the center meridian of the map, meaning we can fig
We can use this [map](https://www.arcgis.com/apps/View/index.html?appid=7fa64a25efd0420896c3336dc2238475) to check out different UTM zones. By clicking on the UTM tile you see the central projection. The map central projection is not necessarily in the center of the map. In the case of South Atlantic it begun as only the Falklands islands so the projection for the whole map is UTM 21S (S for South hemisphere) We can use this [map](https://www.arcgis.com/apps/View/index.html?appid=7fa64a25efd0420896c3336dc2238475) to check out different UTM zones. By clicking on the UTM tile you see the central projection. The map central projection is not necessarily in the center of the map. In the case of South Atlantic it begun as only the Falklands islands so the projection for the whole map is UTM 21S (S for South hemisphere)
![FindProjection](https://user-images.githubusercontent.com/20801481/202789407-6471dbd5-7b59-4cc6-8ab6-08d004b6ddad.jpg) ![FindProjection](https://user-images.githubusercontent.com/20801481/202789407-6471dbd5-7b59-4cc6-8ab6-08d004b6ddad.jpg)
### 1.2 Set up your QGIS project
Then it is a matter of making a new project in QGIS and setting the project CRS to be this. Then it is a matter of making a new project in QGIS and setting the project CRS to be this.
![Projection](https://user-images.githubusercontent.com/20801481/189474094-89e78347-23b5-440a-b4b5-44862b472276.JPG) ![Projection](https://user-images.githubusercontent.com/20801481/189474094-89e78347-23b5-440a-b4b5-44862b472276.JPG)
### 1.3 Visualizing your map by using tiles for satmaps or OpenStreetMaps live view
You can add XYZ tiles from this python script to add in a bunch of online satmap tile layers you can use: https://raw.githubusercontent.com/klakar/QGIS_resources/master/collections/Geosupportsystem/python/qgis_basemaps.py You can add XYZ tiles from this python script to add in a bunch of online satmap tile layers you can use: https://raw.githubusercontent.com/klakar/QGIS_resources/master/collections/Geosupportsystem/python/qgis_basemaps.py
## 2) Outlining the game area ## 2) Outlining the game area
@ -51,7 +52,7 @@ Make sure you use the project CRS (projection) and that it is a polygon. Also ma
## 3) Oceans ## 3) Oceans
For the ocean I downloaded the OSM Ocean Polygon files (source https://osmdata.openstreetmap.de/data/water-polygons.html). These are WGS84 chunck of ocean. Select all the vector objects that are relevant to the map, and use the Vector->Geoprocessing->Dissolve command to merge the cells into one object. This will output a new temporary layer (can be slow to do). This layer we can now save and reproject it to the relevant UTM projection, like UTM 21S for the Falklands map. Be sure to reproject only after dissolve or you will potentially get gaps in the ocean file. For the ocean I downloaded the OSM Ocean Polygon files (source https://osmdata.openstreetmap.de/data/water-polygons.html). These are WGS84-projected chunks of ocean. Select all the vector objects that are relevant to the map, and use the Vector->Geoprocessing->Dissolve command to merge the cells into one object. This will output a new temporary layer (can be slow to do). This layer we can now save and reproject it to the relevant UTM projection, like UTM 21S for the Falklands map. Be sure to reproject only after dissolve or you will potentially get gaps in the ocean file.
Once you have the ocean file dissolved and projected to the correct UTM projection you can clip it to the game area overlay (Vector -> Geoprocessing -> Clip). Once you have the ocean file dissolved and projected to the correct UTM projection you can clip it to the game area overlay (Vector -> Geoprocessing -> Clip).