*Sbaumer
Message 1 of 2 (1,082 Views)

# Scale Factor (Surveying)

1082 Views, 1 Replies
10-27-2009 08:34 AM
Performing a Loooong route survey about 18 miles. using GPS Louisiana Grid
South Coordinates for survey of route. Was curious if there is a "simple"
way to toggle back and forth between a dwg set up on grid (all of our dwgs)
versus a dwg set up on ground. SF in this area is 0.9999365. makes about 6
feet difference over 18 miles. Would be nice to have just 1 dwg for this.
Becomes a pain with where do you apply the scale factor? Middle of route
somewhere? and importing grid coords into a dwg that may need to be scaled
up for ground coordinates

LDD4
Survey2004
Civil Design 2004
Autodesk map 2004

Sbaumer, PLS
*Robert Martin
Message 2 of 2 (1,082 Views)

# Re: Scale Factor (Surveying)

10-29-2009 05:12 PM in reply to: *Sbaumer
Never done one that big.

I would test this in a copy of the project :-)

Is you scale factor constant?
Or an average?

I would guess an average for the entire site would be best.
So......

I would draw a line between 2 points on either end of the job.

Get a good Grid and Ground distance on that line.

Create a new dwg draw a line between those 2 points.

Draw a circle at the midpoint of that line with a diameter of the ground
distance.
Extend the line to the circle.

Insert you grid dwg do not explode

Scale your inserted dwg to the new line using the midpoint as the basepoint.

Explode your dwg and run checkpoints.

You are now on ground. If more field work is required the GPS will need to
be localized
to these points. In topsurv I check keep a scale of 1 to 1, shot 2 points,
hold one for elev, use a geoid, check several others
and this works great. But most salesmen and support will tell you to use
multiple points for a localization.

This sounds like a good job for VRS

Good Luck

"Sbaumer" wrote in message
news:6278860@discussion.autodesk.com...
> Performing a Loooong route survey about 18 miles. using GPS Louisiana Grid
> South Coordinates for survey of route. Was curious if there is a "simple"
> way to toggle back and forth between a dwg set up on grid (all of our
> dwgs) versus a dwg set up on ground. SF in this area is 0.9999365. makes
> about 6 feet difference over 18 miles. Would be nice to have just 1 dwg
> for this. Becomes a pain with where do you apply the scale factor? Middle
> of route somewhere? and importing grid coords into a dwg that may need to
> be scaled up for ground coordinates
>
> LDD4
> Survey2004
> Civil Design 2004
> Autodesk map 2004
>
>
>
> Sbaumer, PLS
>
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