AutoCAD 2007/2008/2009

Active Member
Posts: 8
Registered: ‎04-12-2006
Message 1 of 8 (4,055 Views)

Flatten Z and Elevation

4055 Views, 7 Replies
03-11-2010 03:21 PM
The drawing I've been working on for over a year has recently started giving me numerous problems related to Z coordinates and Elevations. This is meant to be a 2D cad file with no three dimensional information in it. For whatever reason now a number of polylines are showing as being at Elevation: -33025'-8 3/4". Most of the rest of the lines,arcs,polylines and blocks are all at Elevation: 0" or at Start/Center/End Z: 0.

Depending on the line if I move it myself to -33025'-8 3/4" in the properties it will function correctly and allow me to trim/offset/snap to it. If the lines are not at the same Elevation/Z I'm not able to snap/trim/etc. I've tried the command "flatten" from Express tools and while I select everything and say "No" for hidden lines when AutoCAD finishes the flattening process the polylines/lines/arcs are still at various Elevations/Z. Is there any other way to bring all lines/xrefs/blocks/etc to one Elevation/Z level? I cannot select everything and change from the properties menu as the Elevation/Z area is not present.

Thanks for any help.
Valued Mentor
Posts: 503
Registered: ‎10-04-2007
Message 2 of 8 (4,053 Views)

Re: Flatten Z and Elevation

03-11-2010 04:22 PM in reply to: thome50
What I normally do is select all, go to properties and at the very top of the properties there's a list of all the types of entities: lines, plines, text etc... If you go through the list one by one, you can adjust the Z values that way. Hope that helps.
Active Member
Posts: 8
Registered: ‎04-12-2006
Message 3 of 8 (4,053 Views)

Re: Flatten Z and Elevation

03-11-2010 04:44 PM in reply to: thome50
Thanks, I did not know about this way of changing properties of different drawing elements. I went through and did this technique and changed all Z values and elevations to 0. (Except the arc as that would only let me change the Center Z value, not the start or end)

The problem being when I do this a few lines/polylines/arcs disappear from model space. (Less than 5%) The bigger problem is that when I then go to my existing paperspace sheets with viewports there are roughly 70% of the lines/polylines/arcs that are missing. I've checked that all of my layers are on and nothing is turned off in either the sheet or viewports. If I create a new viewport all the elements are coming through just fine. This would be ok except for the fact that this is the base file for my project and I've got roughly 50 different files that link to this and I really don't want to go through and redo 50+ viewports.

Thanks for the reply regardless as I learned something from the comment.
*Expert Elite*
Posts: 969
Registered: ‎03-25-2009
Message 4 of 8 (4,053 Views)

Re: Flatten Z and Elevation

03-12-2010 04:44 AM in reply to: thome50
You can try CHZ20
Posts: 2,699
Registered: ‎04-14-2009
Message 5 of 8 (4,054 Views)

Re: Flatten Z and Elevation

03-12-2010 07:43 AM in reply to: thome50
Have you looked into the OSNAPZ and TREEDEPTH variables?
I hope my info was useful, but if by some odd chance it actually solved your issue, feel free to mark your post as "Accept as Solution". Thanks! :smileyhappy:
Active Member
Posts: 8
Registered: ‎04-12-2006
Message 6 of 8 (4,055 Views)

Re: Flatten Z and Elevation

03-12-2010 08:54 AM in reply to: thome50
Thanks for this link. I installed and tried this and used the change z variable option. It did change all of the z values but they are not consistent. They went from being something such as "-33045 1/4" to now being "3/16" or "3/4", all fractions. Even z variables that were previously ok and set to "0" are now changed randomly. I didn't notice any options to select what z value I wanted. Am I missing something?

Thanks for the great list of resources regardless.
*Expert Elite*
Posts: 969
Registered: ‎03-25-2009
Message 7 of 8 (4,055 Views)

Re: Flatten Z and Elevation

03-13-2010 04:27 AM in reply to: thome50
Please do not select "Set radom Z value",
Just use it with its default settings.
New Member
Posts: 1
Registered: ‎12-28-2012
Message 8 of 8 (2,658 Views)

Re: Flatten Z and Elevation

12-28-2012 11:06 AM in reply to: thome50

I receive drawings from other contractors and some of them always send me their drawings with the Z coordinate all messed up. When I open the drawings and I'm not in any command, and have my properties box open, under VIEW it tells me my Center Coordinates for X Y and Z. These drawings I get will say Center Z is at 1.03345E10 or something like that.


I used TREEDEPTH command to change that Z value to 0. When I entered the command it said my center Z was at 3020, so I entered 0, and now my properties box says my Center Z is at 0. This now allows me to dimension, and be able to grab my dimension grips in all locations. I haven't figured out how to fix the dimensions and text and leaders that were created at Center Z being 1.03345E10, I would assume those would need to be recreated at Center Z of 0. Then they will be grippable.


Also the trick of selecting all and then selecting which objects to modify in properties drop down bar at the top of the properties box, whether it's lines arcs, text, etc. That works only so well, somtimes blocks do not like to move to Z coordinate of 0 and usually dimensions will be messed up still. Z Centers of arcs and circles should be at 0, but you can't change splines and other objects as easily.


Thanks for the helpful command Modman_4

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