Clean Survey

[ARCHdoc]

Hi all,

I thought I would follow up on the discussion from the last Revit meeting regarding "clean" surveys and would like to share the process that we use to create a suitable cad file to link into Revit.

I would like to think that others may do the same with any tips or systems that they use for a better working project.

1) Open the supplied survey (presumed CAD file)
2) Save AS. We typically save this file to be used a Revit link file and will name as such. "project number"_rlink_survey.dwg
3) Thaw all layers.
4) Turn on all Layers.
5) Select everything in model space and explode. This may need to be done more than once as some surveyors tend to use blocks and attributes inside blocks.
6) Determin the scale. Usually surveyors like to draw in meters, simply select a line and view the length in the properties dialogue box. If the line length is 4 and you work in mm it should be 4000, So scale the entire drawings by 1000.
7) Relocate the linework if you are able to move the survey in the cad file closer to the origin 0,0 then do this. (some clients insit on leaving the site true to real world co-ordinates with 0,0 as specific Datum) Moving the 0,0 origin by using the UCS does not generally work Revit will use the WCS 0,0 in the cad file.
"Erase All"
In your command line type E (starts the erase command) then hit enter.
Then type ALL (this selects everthing in the cad file. Including all items that may be in paper space) hit enter.
Then type R (remove objects) This will aloow you to remove the items you do not wat to erase.
Simply pick the items you want to retain or use a bounding or crossing box to select multiple items.
Then hit enter.
9) Purge and Audit the cad file.
10) The drawing will now be clean of everything you do not want and you can start to weed out additional items individually.
11) We tend to only retain minor and major contours, along with all boundary lines (as the survey is generally included as a drafting view on its own sheet in the final project with all infromation)
12) Ensure the contours are set at the correct elevations in 3D.
13) Select all remaining linework, points etc and move to layer "0", Linetype by layer, Colour by Layer.
14) Purge and Audit.
15) Save.

This will give you a clean file to link into your Revit project to create your toposurface and help to reduce any errors that may occur.
I hope people find this helpfull.

[mruehr]

Great
i thought i add this too as the training is different at times

use a seperate Site revit project and link it into your building Project
more detail at the next Meeting
 
this is from David Conant from autodesk and L.Reiz Revit inventor

The GospelFactory says:
This is one place where you have to follow the rules.
Revit's internal calculations do not like very large coordinate numbers.
There are many number systems
used in an app like Revit, some for calculating values, some for driving
the display, etc. In some cases
these systems differ in the precision of the numbers they can use.
When numeric values are small,
these differences in precision are insignificant. When numbers get
large, the differences while still small
on a percentage basis become large enough to effect the results of
display and operations. Thus, it is
important to keep your Revit project near Revit's origin. (near means
within 1 mile/1.6km) Revit's origin
is near the centre of the space made by the elevation symbols in the
default template.
The Rules
ı Always build your building near the starting point of the default
template.
ı Model it with Project North pointing directly up. (lay it out as you
would have it appear on sheets)
ı If you are using a dwg based site, Link your site file Center To
Center.
ı Move or rotate the SITE under your project until it is correctly
positioned relative to the building.
(do not move or rotate the project itself).
ı Use the Acquire Coordinates tool and pick the site.
This will set your project's shared coordinated to those of the dwg's
wcs. True North will be the dwg's Y
axis. Now your building knows where the dwg 0,0 is, but it can still
record its own information in well
behaving small numbers. It knows and can orient to either True North,
or Project North. Once the
shared coordinates are set, subsequent imports can be made origin to
origin using shared
coordinates.
__________________
David Conant
Autodesk Revit