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@Tamsin Slatterthanks for your work on this, absolutley huge learning curve, but very interesting indeed.

 

As a big ask, are you able to post a sample file where you've got this set-up correct? I'd be very interested in pulling VW into my GIS workflow. At the moment when I've done drone surveys and I have either a point cloud, or a mesh, I generally import it in at a x/y 0,0 Local co-ordinate system (otherwise it's miles away from the internal origin, with all the usual issues) So I would really like to be able to import these to a globally correct, geo-refenced layer.

 

Thanks again for your brilliant description. I'm trying this out now!

 

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In haste - rushing to another meeting - will do - just tried to upload examples, but it failed - will investigate later!

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Thanks so much for your investigation on this @Tamsin Slatter - it's massively appreciated, and the results will make a huge difference in our ability to integrate our current VW CAD work into a GIS system! I've undertaken similar testing and it's worked really well.

 

One of the interesting parts of this in particular for me is that IF aligning the User Origin in metres maintains accurate X, Y positioning within a geolocated file... by implication then once this is set up, we could easily move GIS stakes etc and other objects in Eastings and Northings also by utilising the X,Y position in metres, and still be able to accurately geo-reference and extract the lat/long values if we wanted to - which is a HUGE development. Really exciting stuff!

 

Also delighted to hear about the integration of this feature in SP2! Thanks Engineering team! 

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48 minutes ago, Tamsin Slatter said:

Morning all.

I have had a chat with our engineer and done some more testing myself.

 

For the British National Grid, if you align the User Origin, with the Easting and Northing Origin within the Geographic Coordinate System (EPSG code 27700 - the default in the UK templates), CAD drawing within that coordinate system will have the correct X and Y coordinates on export to DWG. So, if you are sending stuff back to someone who has no concept of GIS systems and their software does not use it, this will be fine.

 

The issue currently, within SP1, is that there is not easy way to align the User Origin with the Geographic Coordinate System, because you can't see it and there is nothing to snap to. But there is a way to do it (details below). Even better though, from SP2, there WILL be a way to do this within the Tools > Origin > User Origin command (thank you engineering team!)

 

Here's how to do this in SP1:

  1. Open a UK template - this will already have the default EPSG 27700 code to set the geographic coordinate system to British National Grid.
  2. Set the Document Units to Meters, with an appropriate precision.
  3. Import your DWG using the Document Contains Georeferenced Geometry option on the import dialog. This will import the DWG into the geographic coordinate system. Also import any Shapefiles if you are using those.
  4. Use the Geolocate tool to move the INTERNAL origin close to your geometry (just click on the drawing). This will not change any coordinates with in the Easting and Northing coordinates - it simply ensures that the geometry is close to the internal origin and avoids the traditional problems with any CAD system of placing a huge calculation burden on the system with every move of the mouse.
  5. At this point, the User Coordinate System (User Origin) and the rulers will not show anything relevant. Don't panic!
  6. Choose Tools > Origin > User Origin and choose the option to set it by next click. Click on the Internal Origin, to align it with the Internal Origin. (Again, don't panic - this is temporary!)
  7. Use the Stake tool and place a Stake on the Internal Origin (and User Origin). Set it to display Coordinate Point (E,N) in Meters with full precision.
  8. Make a note of the E and N numbers from the Stake (screenshot, write it down, or ungroup it to get the text - whichever method you prefer).
  9. Now change the X and Y coordinates of the Stake to match the E and N, but with a negative. For example: If E is 10000 and N is 5000, set X to -10000 and Y to -5000. This will move the stake to the origin of the Geographic Coordinate System, and give you a valuable snap point.
  10. The Stake should still be selected, so click Fit to Objects to find it.
  11. Now run Tools > Origin > Internal Origin again and choose again the option to set it by next click.
  12. Click on the Insertion point of the Stake. The User Origin is now aligned with the Geographic Coordinate System. The rulers will show relevant values.

Using the above method, I was then able to draw new stuff over my DWG, and then export the drawing back to DWG. I then imported it into a blank file WITHOUT using the Document Contains Georeferenced Geometry option, and all was good. The coordinates of the site matched, and the size and position of my new stuff also matched.

 

I do hope this helps clear up confusion and doesn't add to it!

 

This is pretty similar to what I did, but I shortened a step... which may be incorrect but thought I'd share just incase! 

 

At step 6 - Tools > Origin > User Origin - even after I geolocated, the top of the prompt box for this tells me "the user origin is co-incident (the same as) the internal origin". So if you have this as well, it might save you a click 😂

Screenshot 2019-10-23 at 11.05.21.png

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