If a CAD file fails to process or appears in an incorrect location, the primary cause is often a spatial definition error.
This guide outlines how to identify whether a file is unreferenced, assigned an incorrect Coordinate Reference System (CRS), or contains stray data that distorts the model's extents.
1. Common spatial alignment issues
Incorrect CRS: The model is georeferenced, but the coordinates correspond to a different CRS than the one assigned to your project. This results in the model appearing in the wrong geographic location.
Unreferenced Data: The model was authored using a local grid or arbitrary origin (e.g., 0,0 or 100,100). Because these coordinates have no "real-world" global context, the model will typically appear at the origin of the project's CRS.
Stray data at the origin: The model is correctly georeferenced, but "junk" geometry, empty blocks, or unreferenced elements remain at the (0,0,0) origin. This significantly inflates the file's bounding box (extents), leading to navigation failures and visualisation errors within the platform.
2. Diagnostic procedure: Querying coordinates
Step 1: Identify your Sensat project CRS
Navigate to your Sensat workspaces homepage.
Click the three-dot menu at the top of the left-hand side panel.
Select Project Settings.
Note the CRS name (e.g. EPSG:27700).
Step 2: Query the CAD file
Open your file in an application such as AutoCAD or Civil 3D and perform the following:
Zoom extents: Double-click the mouse scroll wheel to fit everything on screen.
Check a point: Type
ID, press Enter, and click a known corner of your model. Note the X, Y, Z coordinates.Check the bounds: Type
EXTMINandEXTMAXto see the minimum and maximum coordinates of the entire drawing.
The alignment diagnosis
If query results show... | The issue is... |
| Unreferenced data |
| Incorrect CRS |
| Stray data at origin |
3. Coordinate verification via Map Viewer
Before re-uploading to Sensat, verify your coordinates against an external spatial reference like EPSG.io.
Important note on units: Sensat can handle various units (e.g., mm, cm, m, ft) during upload. However, most map viewers and CRS definitions use Meters. The unit conversion below is only required for this verification step so you can accurately compare your CAD data to the map.
Manual unit conversion: If your CAD file is in millimeters, divide your AutoCAD
IDcoordinates by 1000 to get the meter equivalent.Verify site location: Access the EPSG.io Map Viewer and select the correct project CRS from the bottom menu. Input your converted X and Y coordinates.
Validation: If the map pans to the correct project site, the coordinates are accurate. If it pans to an unexpected location or the CRS origin, the file requires re-referencing or CRS correction.
4. Resolution: Applying georeferencing
If your diagnosis confirms that the file is unreferenced or using the incorrect CRS, you will need to re-align the data before re-uploading.
For Revit users: Use the "Specify Coordinates at Point" tool to align your model with a known site coordinate. See: [How to Geo-reference a file in Revit].
For AutoCAD/Civil 3D users: You may need to manually move and rotate your model using the
ALIGNcommand to match surveyed site markers.For GIS users: Ensure the export settings in your GIS software match the EPSG code found in your Sensat Project Settings.
5. Resolution: Removing "stray" data
If your coordinates are correct but you have "stray" data at (0,0,0) inflating your file bounds, follow these steps:
Select only the data you want to keep (click and drag a box around the site).
Explode: Type
EXPLODEand hit Enter. This breaks down blocks that might be hiding stray data.Export Clean File: While the data is still selected, type
WBLOCK.Save: Choose a new filename. This creates a file containing only your selected model, leaving any "junk" at the origin behind.