Allow more than two reference points when georeferencing cad files. Make it more like georeferencing an image. Make it so that you can use unlimited reference points.
I newer understood why there are only 2 control points allowed for georeferencing CAD files... But long live Spatial Analyst, although it would be easier to georeference the CAD layer before importing it into the geodatabase, especially for CAD data with a ton of layers which need to be imported in separate feature classes.
The georeferencing quality of CAD drawings can be arbitrary if the links are limited to 2. In some cases, you may not have exact target features, e.g. when referencing floor plans to cadastral maps or aerial photographs. In these cases it would be helpful if the georeferencing can be improved by using more control links and averaging the parameters of the transformation (as in transform, but maintaining the properties of a similarity tranformation).
"The purpose for georeferencing a CAD dataset is to accurately overlay the CAD drawing with existing spatial data without skewing its geometry. If a more complex transformation is needed, you can load the data into a geodatabase and use the Modify Features pane."
I suppose the idea then is simply so the data doesn't have to be loaded into a geodatabase first, correct?
not quite - not having to load the CAD drawing into a GDB is just a side aspect (of convenience). The main point is to get a better similarity transformation (not sure about the correct mathematical terminology - the same type of transform which maintains aspect ratios). Better meaning a better overall fit, not just fitting 2 control points.
Thanks, Everyone, for reaching out on various aspects of this idea.
The purpose for georeferencing CAD datasets continues to be for accurately overlaying the CAD drawing with existing spatial data without skewing the CAD geometry. If more than two control points are included as part of georeferencing, then any control points >2 could end up skewing the CAD geometry.
We very much recognize that there are instances where you are okay with introducing skew, such as transforming the CAD to match the aerial. For these uses, the recommended approaches remain to either have the desired transformations carried out "upstream" in the CAD environment, or load the CAD dataset into a geodatabase and use the Modify Features tools.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.
