draw accurate floor plan for existing building

[aniss9999]

Hi, I need to draw an accurate floor plan for an existing building because we want to calculate total costs for wiring. Most angles seem right but some aren't. Also the area isn't rectangular but it is made of many "triangular room" here and there. I am trying to draw a sketch with distances from corner-to-corner but I realize this method is not accurate and distances don't match in autocad drawing. Can I ask you please is there any method to get maximum accuracy? do I have to work with Cartesian coordinates of each corner? do I have to buy some expensive GPS material to do this? I Thanks.

[dbroad · Accepted solution]

All the estimating books I've read indicate that for cost estimating, an accuracy of 10% is about as much as you can expect, even with the best drawings.  Unless you are way off in actual dimensions, I doubt that slight angular problems will be significant in creating a cost estimate for wiring.

If you need super accuracy, I believe working from point clouds are the method of choice.

[aniss9999]

Thank you M. dbroad. Point Clouds is interesting I'm checking if there is some cheap materiel to scan physical surfaces and export points data.

[mattsahli]

great question. i am faced with a similar issue. i need EXACT messurments in a grocery store with shelving that has been moved and beaten up for 40 years. not for the flooring sq ft but to better lay the job out for my employies, without my being there the whole job through. I invision a triangulation system that would allow me to set up three antenas and use some form of repeter device to allow me to acuratlly lay out all imperfections of a heavily used building in all three axis. I guess my question is has anyone seen anything of this nature? or would know the direction to point me in. would also help original poster. Cheers.       

[orrell_r]

http://www.3dlasermapping.com/zeb1-indoor-mapping/

http://www.faro.com/products/3d-surveying/laser-scanner-faro-focus-3d/overview