Friday, November 30, 2007

Point Transformation

First of all I would like to thank Chris for allowing me to post my Civil 3D reminders here as well. I have referenced Chris' blog countless time to help me remember labeling ideas, routines, etc.
Well have you ever struggled with the Transformation of points within Civil 3d? Well I have, so the purpose of this post goes along with Chris' theme of posting helpful reminders for the future.

Properly set the current drawing units and coordinate settings, located within the Settings tab of the prospector. (i.e. Where in the world are you or where were your points shot?)

Create an appropriate "Point File Format" (This is found in the settings or if you go to Points-> Import/Export Point -> Transfer Points, you can choose manage and then create a new user format).

-For my handheld points, I created a "Point File Format" that was Lat Longs -> WGS84 datum, Lat-Long, West Positive; Degrees -180 to +180. I then choose "deliminated by" and then placed a comma in the box. Next I set up the format of my source "Point File"; Point Number, DECGEG Latitude, DECDEG Longitude, Point Elevation, Raw Description.

-Since my project is located in San Bernardino County, I was able to use CalTrans' website to determine that I am in Zone 5 of the Californina State Plane and I am using the US Foot for my units and am using NAD83. As I did above, I need to create a new "Point File Format" for my NAD83 California State Planes, Zone V, US Foot format. Again I choose "deliminated by" and then placed a comma in the box and then set up the format for my destination "Point File"; Point Number, Grid Northing, Grid Easting, Point Elevation, Raw Description.

Then I click "OK" within the Transfer Command. A new text file is created with the Transformed Points.

Check results!
The text file titled "two" is the original point coordiante from the Handheld GPS device. The file titled "test" is the output from the transformation.

Yep, it's that easy!

Alternatively you can import your points from your handheld GPS unit using a drawing that is setup for Lats and Longs and then "Export" using the "Point File Format" that you created above.

BAM! You now have a point file that is on the coordinate system that corresponds to your design coordinate system.


Anonymous said...

This idea of point transformation greatly intrigues me. Can I transform points to adjust northings of an ascii point file (P,N,E,Z,D) by a constant?
ie: point coordinate 99100,100 would become 100,100. I am using a 3rd party software to to the batch conversions, but would LOVE a way to do it within Civil 3D.
Thank you.

J-Fussel said...

I may be wrong, but have you tried to use the move command or the align command? If you have and you had issues, did you try to change the 3d geometry within the object style for the point to be "flatten to elevation?"

Good Luck.


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