I'm using Power Geopak SS4 .878. My project started with international feet as my working and storage units but with coordinates matching survey feet. I've converted all files to survey feet using a VBA macro. I know that you can expect to get a message when attaching a survey feet file to an international feet file and vice versa, warning you that the coordinates are going to be off. I haven't been getting that message.
My existing DTM from survey is in one file. In my corridor file for phase 6, I have complex terrain model that serves to simulate the existing terrain at the beginning of phase 6. (This seems to affect other phases too, but at the moment I'm working in phase 6.) As mentioned, both files use survey feet.
I took a look at corresponding points out on the fringe. I measured the distance, which turned out to be exactly the value of the lower (southwesterly) coordinate*[(1-2e-6)^-1 - 1]. The factor here suggests that one file must be survey and the other international. But when I attached the files, no warning showed up. In the references list, I noticed that the DTM file scale is 1:1 whether True Scale is on or off. (Otherwise, when the units differ, it flipflops between 1:1 and 1:1.000 002, or between 1:1 and 1.000 002:1.)
To clarify, the survey DTM holds the larger coordinates. Something in the system (apparently) is telling the complex terrain that the survey DTM's points are in international feet. Therefore, the complex terrain model uses smaller values for coordinates.
Apparent root of the problem:
In my phase 6 corridor file, where I also have created the complex terrain model, my survey DTM is attached with 1:1 scaling. The complex terrain model is scaled down as mentioned, so looking at a fringe point, I see two distinct points: one from the survey, one from the slightly smaller scale. I have no explanation for this behavior.
Further exploration:
I took the time to get into VBA to confirm the units. In both the survey DTM file and the corridor file,
MasterUnit.UnitsPerBaseNumerator = 39370 MasterUnit.UnitsPerBaseDenominator = 12000
to represent 39.37 inches per meter over 12 inches per foot. Same for StorageUnit.
SubUnit.UnitsPerBaseNumerator = 39370 Subunit.UnitsPerBaseDenominator = 1200
to represent 39.37 inches per meter over 1.2 inches per tenth of a foot.
Any ideas on what might be the problem here? Any ideas on how to fix this?