I have a project where I was told by my engineer client that the local bench marks were NAVD 88.?ÿ I did the job, topo, etc., and finally checked the BM's with GPS. Turns out they're off by over a foot.?ÿ I know, I should've checked earlier, but I didn't.?ÿ Occasionally, I initially trust someone, but seems that most times I get burnt when doing so.?ÿ Case in point.
I'm either going to just reference the datum to something else, or going to actually put the project back on NAVD 88.?ÿ If I do that, is there a quick way in Carlson to just bump the whole surface down to the correct datum??ÿ I know I can easily change all of the points by a certain elevation shift.?ÿ But the breaklines will still be at the bogus elevations, and to re-do each one will be a bit of a pain.
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I also checked into some published BM's with GPS, and the checks confirm that the GPS elevation is good.
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In the Triangulation file utilities, you can add or subtract the surface to adjust.?ÿ Just move the linework using the displacement option or I use, in your case, move all from 0,0,1 to 0,0,0
Yes, me too, same as Jason.
Thaw / Isolate the triangulation surface lines and triangles.
Move. ?ÿAll.
From base point 0,0,0
To base point 0,0,-1.00
Thanks, Jason & Brad.?ÿ I'll use one of those methods.?ÿ
I guess I thought Carlson would have an option to change the datum, which would adjust everything in one routine.?ÿ They seem to have a solution for almost everything
Thanks
If the Engineer gave you what essentially is a project datum it may be best to not move everything?
Typically, yes. There's more to the story, but that's just how I framed it. This is a site that's on its on and isolated, etc.
Thanks for the tip, though.
"Move" does that. Adjust all your field points, ignoring zero elevations with the translate command. Set your breakline layer on and create a new 3D line from a revised point that is a breakline endpoint, make the new line a different color, freeze everything but the breakline layer then pick all the breaklines, "Move" by "endpoint" to "endpoint" erase the odd color and all breakline will be moved in elevation. Then recreate any contours.
Paul in PA
There is a way to adjust the elevation of your surface so you don't need to recreate it.
Under the Surface menu, go to Triangulation File Utilities and load your surface tin file. Click Next, then click Subtract, click Value, then in the next box you can enter the value by which you want to lower your surface. This will adjust your surface ONLY. You might need to perform a Surface Redraw to update the triangles and contour lines in the drawing. To make sure your breaklines and points are adjusted, perform the move commands as other posts here have shown.
There's a lot you can do in the Triangulation File Utilities. If you need to translate, rotate or merge tin files, that's where to go.
Keith
