Use this forum to ask questions about DataCAD 18 and DataCAD LT 18.
#68858 by jimgoodman
Tue May 10, 2016 9:53 am
I am working with a civil engineer on two projects and we are having some accuracy issues when going back and forth between their AutoCAD and DataCAD.

The civil drawing origin point for one project is approximately 2.485822e9' and 199.25.48 degrees away from the DataCAD origin. Would this distance create inaccuracies in DataCAD from file to file?
#68924 by Mark Bell
Thu May 19, 2016 9:52 pm
Hello Jim,

What we've ended up doing in these situations is importing the civil dwgs as xrefs then we can locate them relative to the DataCAD drawing which is close to the abs. zero location. As you probably know, once the drawing gets further away from the abs. zero you get all types of distortions and anomalies happening.
#68929 by jimgoodman
Fri May 20, 2016 7:39 am

I thought that issue had been either resolved when the DataCAD database was changed to double precision many versions ago. Dave or Mark??????????
#68930 by David A. Giesselman
Fri May 20, 2016 9:38 am
6.5 million feet away (2,485,822,000/32") from absolute zero is a very large number when you need a precision of 1/32" or smaller, even in the world of double-precision math.

#68931 by jimgoodman
Fri May 20, 2016 9:58 am
Thanks Dave

I usually import the civil files as XRefs and insert them into our drawings close to the DataCAD origin so there shouldn't be a problem but I am having a minor issue with one engineer's drawings.
#68933 by dmartens
Fri May 20, 2016 2:25 pm
Civil plans tend to be so far from absolute zero for a couple of reasons. The software used to input your field shots and create topo can't use negative coordinates. So the software advised setting your base point at 5000,5000 to avoid this. Also depending on what state you are in, some plans (especially on-site sewage disposal) had to align with the state plane coordinate grid and a GPS point given for the center of the disposal field. This way the state (VT in this case) can map all water supply and wastewater systems state wide.
Maybe you can get your engineer to move the plan to 0,0 before he sends it to you and then he can move it back when he receives it from you.
#68934 by joshhuggins
Fri May 20, 2016 3:38 pm
Yeah I get all that but still the farthest distance across any state here in the US is like 800-900 miles across Texas or maybe some of the islands to the mainland of Alaska might come close to 1200 miles. At some point someone needs to have the brains to say 'o.k. this distance relationship is kind of beyond the scope of normal' even for civil drawings. Maybe for a single reference file if it's truly needed, but not a main working file. Like you said usually there is a grid system to reference to that makes more sense.

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