If you are using Autocad or Civil 3d, go to options/drafting and tun on "Replace Z value with current elevation". This will give you a horizontal measurement using the DIST command while snapping to 3d objects.
Paul in PA, post: 326636, member: 236 wrote: NEGATIVE.
First off I never get wild measurements because my CAD software gives horizontal measurements which is typical for all survey work. You need to either fire your CAD software, your CAD technicians or both.
My CAD also is capable of ignoring all points at Zero elevation.
Are you trying to solve a problem or create a problem?
Paul in PA
The last time I used vanilla AutoCAD the distance command gave slope distances. I believe this is still the case. Most of the users of my surveys use vanilla AutoCAD or LT.
Not trying to create a problem just gaining insight into how customers may misuse my surveys. If you see that as trying to create a problem just carry on as you are no difference to me mate.
We add a description No elev that comes in out CAD as text and are excluded for building the DTM.
We can also give a negative pointnr in the dc, then no elev. is calculated and we only have a 2d point in our CAD.
Chr.
Totalsurv, post: 326635, member: 8202 wrote: I think my question may have been misunderstood. I never use these points as part of the surface model. What I am saying is that in the cad file if a cad tech measures from a zero elevation point to a 3d point they will get a wild measurement.
Set OSNAPZ to 1. This will, simply put, cause you to snap to elevation 0 every time, regardless of what elevation the element is at.
Alternatively, you could set up a styles for non-DTM points that put them all at elevation 0.
My descriptors sort them.
UP = Utility Pole with valid elevation
UPNE = Utility Pole with invalid elevation
UP adds a point to a group TOPO and the point goes on S-ESE-Pts-TOPO
UPNE adds a point to a group LOC and the point goes on S-ESE-Pts-LOC
Totalsurv, post: 326527, member: 8202 wrote: Would be great to hear how others handle this.
Similar to some others, I segregate reflectorless shots by description. In my case, I prepend "|" (pipe symbol) to the description. That makes it easy to distinguish them from ground shots while retaining the description content. I retain the elevation because I often want to know the heights of wires, crossarms, eaves, etc., I just don't want them in the DTM.
I put a "Z" in front of my bad elevation shots. I have my description keys setup to recognize a few of my codes that might have a Z in front of them. e.g. I have a description key for utility poles as "*UP" and light poles as "*LP", so whether I shoot it as LP or ZLP it comes in with a light pole symbol. Now if I were to take a shot and code it CUP, then it would come in as a utility pole... I don't normally shoot CUP shots. I also have a point group called "Ground Shots" and it is setup to exclude Z* shots. I use the Ground Shots point group and breaklines when cutting contours.
Long time lurker. This is my first post, but I have used the great information from this site for the past couple of years, so here's my 2 cents.
Most of our work is topo surveying for bridge and culvert replacements. Not the most sophisticated method, but we use point numbers to separate types of shots. Control have point numbers 1 - 99, prism shots 101 - 999, reflectorless with "good elevations" 1001 - 1999, reflectorless with "bad elevations" 2001 - 2999. Point groups are then created by number in Civil 3D.
It's a lot like handling grid versus local coordinates. Pick a method that can be learned and communicated easily. Ensure that significant errors aren't introduced. Document the heck out of it and don't expect everyone else to do it that way without being instructed.
After all that be ready to learn a better way. There is ALWAYS someone doing something better...
