Django app that imports CAD drawings in Leaflet maps
Show CAD drawings with no geo location in interactive web maps. Change / add layers to drawings, change / add elements to layers, change blocks and change / add it's instances, download changed DXF files with geo location.
There is a lighter version of this app: django-geocad-engine. It is limited in manipulating the drawings (your CAD is better at doing that!), but shows entity data on the map. It downloads geo located DXF and can also download entity data in CSV format.
This app is tested on Django 4.1 and Python 3.10.0. It heavily relies on outstanding ezdxf for handling DXF files, pyproj for geographic projections, django-leaflet as map engine, django-geojson for storing geodata, shapely for polygon verification, django-filebrowser for managing pictures, django-colorfield for admin color fields and django-htmx to manage interactions. I use Bootstrap 5 for styling. I develop this app inside my personal starter project that provides all the libraries you need, along with an authentication engine. If you want to embed django-geocad into your project you will need to make some tweaks.
See requirements.in for required libraries. In your project root type git clone https://github.com/andywar65/djeocad, add djeocad.apps.DjeocadConfig to INSTALLED_APPS and path(_('geocad/'), include('djeocad.urls', namespace = 'djeocad')) to your project urls.py, migrate and collectstatic. You also need to add initial map defaults to settings.py (these are the settings for Rome, change them to your city of choice):
LEAFLET_CONFIG = { "DEFAULT_CENTER": (41.8988, 12.5451), "DEFAULT_ZOOM": 10, "RESET_VIEW": False, }
A satellite tile layer is expected, so you will need a Mapbox token to make it work. Add the token to project/settings.py (I use environs for secrets): MAPBOX_TOKEN = env.str("MAPBOX_TOKEN").
Unauthenticated users can upload DXF files, but it's possible to limit the number of extracted entities by setting DJEOCAD_MAX_ENTITIES = integer (it is 20 by default).
On the navigation bar look for Projects/GeoCAD. You will be presented with a List of all drawings and a List by author, where drawings are just markers on the map. Click on a marker and follow the link in the popup: you will land on the Drawing Detail page, with layers displayed on the map. Layers may be switched on and off.
Unauthenticated users can upload a drawing (to modify it see further paragraph). To create a Drawing you will need a DXF file in ASCII format. DXF is a drawing exchange format widely used in CAD applications.
If geodata is embedded in the file, the drawing will be imported in the exact geographical location. If geodata is unavailable, you will have to insert it manually: to geolocate the drawing you need to define a point on the drawing of known Latitude / Longitude. Mark the point on the map and insert it's coordinates with respect to DXF World Coordinate System origin (0,0,0). A good position for the Reference / Design point could be the cornerstone of a building, or another geographic landmark nearby the entities of your drawing.
Check also the rotation of the drawing with respect to the True North: it is typical to orient the drawings most conveniently for drafting purposes, unrespectful of True North. Please note that in CAD counterclockwise rotations are positive, so if you have to rotate the drawing clockwise to orient it correctly, you will have to enter a negative angle.
Try to upload files with few entities at the building scale, as the conversion may be unaccurate for small items (units must be in meters).
Add a Title and a short description (if you are authenticated you can also check the drawing as Private to prevent other users from viewing it). The Private flag also unlimits the number of extracted entities.
Press the Save button. If all goes well the DXF file will be extracted and a list of Layers will be attached to your drawing. Each layer inherits the Name and color originally assigned in CAD. POINT, ARC, CIRCLE, ELLIPSE, SPLINE, 3DFACE, HATCH, LINE and LWPOLYLINE entities are visible on the map panel, where they inherit layer color. If unnested BLOCKS are present in the drawing, they will be extracted and inserted on respective layer.
In Drawing Detail view it is possible to download back the (eventually modified) DXF file. Some limitations apply: curved entities will be approximated to LWPOLYLINES, Layers will have True Colors instead of ACI Colors and entities in blocks will all belong to layer 0. Closed polylines will be transformed in hatches. On the other hand, GeoData will be associated to the DXF, so if you upload the file again, it will be automatically located on the map.
If you are authenticated and granted GeoCAD Manager permissions, you can modify the drawings you have personally uploaded.
You can modify the drawing Title, image and descripition, along with the DXF source file or geographic location / rotation. You can check the drawing as Private to prevent others from viewing it.
You can create, update and delete Layers associated to the drawing. You can access layer Name, color and linetype (continuous and dashed are the allowed types), and modify entity geometries. Some limitations occour: Layer 0 can't be deleted or renamed and you can't have duplicate layer names in the same drawing (that's consistent with CAD behaviour).
If you want to create a new BLOCK, make a Layer first, then transform it to block (an instance of the block will replace the layer). Blocks share the same model as Layers, so they can be modified. When updating a Block you will be able to access it's instances. Apart from normal CRUD operations, you can also explode an instance: the instance will be deleted, but it's entities will be transferred to insertion layer (this is common practice in CAD).
Beware that if a download is performed, the original file will be replaced with the downloaded copy, so you will eventually lose some data.
Geodata can be stored in DXF, but ezdxf library can't deal with all kind of coordinate reference systems (CRS). If Geodata is not found in the file (or if the CRS is not compatible) django-geocad asks for user input: the location of a point both on the map and on the drawing coordinates system, and the rotation with respect to True North. The pyproj library hands over the best Universal Transverse Mercator CRS for the location (UTM is compatible with ezdxf). Thanks to UTM, Reference / Design Point and rotation input, Geodata can be built from scratch and incorporated into the file.
- Design point written in Geodata
- Change layers / blocks / instances from drawing detail
- Fixed recursion error on Layer delete
- Correct explanation of Rotation field
- Hatch support
- Correct geometry type in Leaflet.draw module
- Layer linetypes
- More entity types
- All transformations use
ezdxfandpyprojmethods Geodataare stored in downloaded file
- Fixed bug in drawing download
- Upload files without login
- Transform layer to block
- C*UD views need permissions
- CRUD of block instances
- Ability to switch single layers on/off in drawing detail view
- Extended CRUD on frontend
- Extract BLOCKS
- Extract ARC and CIRCLE entities
- Download drawings as DXF
- Open to suggestions