Parcels - LandXML translation for ground to grid...

[MikeKitchen5860]

Hi all

I'm trying to work out a better workflow for the many small subdivisions I deal with. Since lots and road designs are most often done at ground, that's how my topo surveys often arrive. However, my planning work (storm drainage studies, etc...) rely on things being projected to grid to mesh with GIS, air photos, etc... Surfaces seem to translate on landXML import (provided it's just scaling). However, parcels will not. Is there any reason for this? I'd love to know. Is it that the arcs tend to get ellipse-ized with scaling?

Thanks

Mike KItchen

Osprey Engineering Inc.

Civil 3D 2021.2

[Pointdump]

Mike,
You can design in Ground and still bring in GIS Data by creating a Custom Ground System with an Affine Post-Processor. Alan Gilbert shows the Reader's Digest version >>>Here<<<.
Dave

[MikeKitchen5860]

Hi Dave( @Pointdump )

Thanks for the reply. So, a good workflow for such a job would be:

1. Set up a ground-level coordinate system (I'm in western Canada so my work is always in Transverse Mercator zones) using the grid-to-ground combined factor as provided by the surveyor.

2. Apply that coordinate system to all my drawings where I'll be referencing other GIS-type data.

Basically, each project would have its own coordinate system based on the combined factor used in the survey I'm working from (instead of using the standard coordinate systems and applying translations). Correct? And that would mean I (mostly) avoid having to reproject/translate my parcels.

Thanks

Mike

[Pointdump · Accepted solution]

Mike,
"...my work is always in Transverse Mercator zones..."
The Affine Post-Processor is available in both Transverse Mercator and Lambert Conformal Conic.
"...each project would have its own coordinate system..."
Yes. To figure the parameters--A0, A1, A2, B0, B1, B2--you'll need 3 points that have both ground and grid coordinates.
"...I (mostly) avoid having to reproject/translate my parcels."
Yes. You'll do all the design work in ground, and have the ability to bring in GIS Shapefiles and Imagery. Even Bing Live Maps will work.
Dave