Point Elevation Trouble

[guy_carleton]

Hi All,

Thanks in advance for taking the time to read my question. I am using AutoCAD 2009 LT. I have a dwg with topo contours and points. Unfortunately, most of the points do not have z values, but I need those. Short of measuring from the topo contours to get elevation (there are a lot of points and this is quite time-consuming) is there a way to get the z values from a combination of thye x and y values and the topo contours? ie. Can I create a surface from the contours and project the points on to the surface, assigning a z value to their properties (or something like that?!?)

PS - I am getting the x and y values and putting them in a spreadsheet using the ID point command - if anyone knows of a way to do it faster/better please let me know! The x,y, and z values are then going in an excel spreadsheet. LISPs are not an option (?) as I am using LT.

Thanks for your help!

Cheers.

[Charles_Shade]

Cocantenation(sp.) from Excel is the way to enter the points into CAD but it reads you are outputting to Excel. You do need the Z coords and there are three ways to get those:
1. Surveyor
2. Topo map
3. Guess
Search here for your needs. This is a subject theat has come up over the years.
Regards, Charles Shade

[Anonymous]

Oh man, PITA.

Anyway, when I need to approximate an elevation for a point, I programmed my
calculator to make it easier.

Basically I measure in a straight line from a known high point (like a topo
line) and a known low point. The point I want the elevation for lies on the
line, between the high and low point.

So then I do this.
High point Elevation = Register A
Low Point Elevaton = Register B
Total line length from high point to low point = Register C
Distance from low point to point in question = Register D

Formula is (in HP RPN)

Reg A Reg B - Reg D Reg C / * Reg B +

Sort of depends what kind of calculator you have.

You could do it in Excel as well.

But it will always be an approximation. Topo lines are approximations at
best anyway.

GC

"guy_carleton" wrote in message news:6222764@discussion.autodesk.com...
> Hi All,
>
> Thanks in advance for taking the time to read my question. I am using
> AutoCAD 2009 LT. I have a dwg with topo contours and points.
> Unfortunately, most of the points do not have z values, but I need those.
> Short of measuring from the topo contours to get elevation (there are a
> lot of points and this is quite time-consuming) is there a way to get the
> z values from a combination of thye x and y values and the topo contours?
> ie. Can I create a surface from the contours and project the points on to
> the surface, assigning a z value to their properties (or something like
> that?!?)
>
> PS - I am getting the x and y values and putting them in a spreadsheet
> using the ID point command - if anyone knows of a way to do it
> faster/better please let me know! The x,y, and z values are then going in
> an excel spreadsheet. LISPs are not an option (?) as I am using LT.
>
> Thanks for your help!
>
> Cheers.

[Modman_4]

Could the OP not draw his grid lines, then set up a second viewport with the UCS perpendicular, then start the line command in that, and then switch to the plan viewport and pick the appint of the contour and the gridline and draw vertically to the grid line? with the WCS in plan, his xyz coordinate would be where the end of the line touches the contour line (see Properties). Rinse and repeat, although that too would be time-consuming...

[Charles_Shade]

Post an example of that dwg.