RiBeneke
Structural
- Nov 18, 1998
- 284
Some of you out there may have tried the new feature in AutoCAD 2002 called trans-spatial dimensioning.
The way it works is that you create your 3-d model, switch to paper space and set up your viewports and system variables correctly, including full associative dimensioning option. Then, working in paper space, you dimension directly onto snap points on your model, and the dimensions are all correct ... that is the theory. It is a great system for complex models as it avoids the need for multiple dimension layers or offset dimension planes in the model space.
However I have encountered a serious problem with it and I wan to warn others : If your dimensions are on to inferred snap points rather than actual associative snap points then your dimensions will not be reliable. For example on a plan of a building, you may have internal walls and would normally dimension on a perpendicular to that wall, which is an inferred point, rather taking the dimension extension across the plan to the actual end of the wall, which is the associative snap point.
I did several drawings using this new method, but with inferred snap points. After plotting them, I took another look before despatching them and found that dimensions had jumped around and attached themselves to other points and the numbers were quite wrong as a result. Checked on Autodesk's discussion forum and found that this is a known problem, and the dimensions may change when a drawing is reloaded or regenerated under these circumstances.
So the warning is : only use this new feature if you can snap directly to object positions.
Any comments ?
The way it works is that you create your 3-d model, switch to paper space and set up your viewports and system variables correctly, including full associative dimensioning option. Then, working in paper space, you dimension directly onto snap points on your model, and the dimensions are all correct ... that is the theory. It is a great system for complex models as it avoids the need for multiple dimension layers or offset dimension planes in the model space.
However I have encountered a serious problem with it and I wan to warn others : If your dimensions are on to inferred snap points rather than actual associative snap points then your dimensions will not be reliable. For example on a plan of a building, you may have internal walls and would normally dimension on a perpendicular to that wall, which is an inferred point, rather taking the dimension extension across the plan to the actual end of the wall, which is the associative snap point.
I did several drawings using this new method, but with inferred snap points. After plotting them, I took another look before despatching them and found that dimensions had jumped around and attached themselves to other points and the numbers were quite wrong as a result. Checked on Autodesk's discussion forum and found that this is a known problem, and the dimensions may change when a drawing is reloaded or regenerated under these circumstances.
So the warning is : only use this new feature if you can snap directly to object positions.
Any comments ?
