As Built survey - 3d Laser Scanning

shane6977

Just wondering has anyone commissioned a 3d laser scan for an As Built Survey?

If so, how did you find it in terms of quality / accuracy?

What time savings were achieved on traditional survey methods?

Supertech

Haven't commissioned or done one, but have seen a couple of in depth demos. Accuracy wise, you'll easily achieve better results than using traditional taped methods, and will certainly match total station accuracy. Time wise, some of the newer models shoot a phenomenal amount of points per second, capturing huge amounts of data. This then needs to be manipulated to extract the useful stuff which you actually want. All of the newer point-cloud software should be fully compatible with BIM which may make extraction simpler. Hire cost is around €400 per day, but that might not include an operator. The key is in the set up, and the specific definition of the information required. On the down side, I find in many cases, that digital surveys are almost 'too' accurate in terms of future use of the drawings as nothing will be square, plumb or parallel. However, if the building is of any significant size, the time savings and accuracy should outweigh any of those minor irritations.

DOCARCH

Supertech wrote: »

I find in many cases, that digital surveys are almost 'too' accurate in terms of future use of the drawings as nothing will be square, plumb or parallel.

+ 1 on this. I have recieved surveys of existing houses from clients which are virtually useless for further use for this reason. You end up spending a lot of time re-drafting/setting up a new layer connecting and squaring lines.

shane6977

thanks for the responses guys.

As you have mentioned above, I am a bit worried about the surveys being "too accurate". However it is a large and complex building which we may need to have surveyed in a short space of time. It might be worth having a sample area surveyed before committing to having the entire building done.

DOCARCH

With a large complex building there may be no alternative but to get a 'digital' survey done but be prepared to spend some desk time tidying up the survey and making it useable...maybe the lesser of two evils!

About 15 years ago I remember doing a survey of a 6 storey mill building. It took 2 of us 5 full days to measure (on site) with pen, paper and measuring tapes, etc.,...mind numbing stuff!...then another week to draw up the survey in the office. In that sort of situation, I would take a 'digital' survey anyday and deal with it.

Supertech

With DOCARCH 100% on this one. If it's of any size or complexity get it scanned. Let the machine capture the data, and have the company pick out the stuff you need. You'll have a decent survey brief written in a fraction of the time it would take to measure it and draw it up. Provide this to the survey company and let them do the tidying - they're the experts.

irishmover

DOCARCH wrote: »

About 15 years ago I remember doing a survey of a 6 storey mill building. It took 2 of us 5 full days to measure (on site) with pen, paper and measuring tapes, etc.,...

As a Surveyor, I am not impressed!..................

To the OP, how did you get on? I specialise in this area, but am over in Australia at the moment doing BIM's. TLS has a great market over here, had an okish one back at home before the downturn. With experience of a cheap (in comparison) scanner which achieves excellent results I'm very interested in finding out how the Irish market is doing as I'm considering setting up my own business at home in 2-3 years.

Depending massively on many parameters the accuracy achievable can be up to 2-3mm but that is time consuming. 10mm is achievable within a half days worth of scanning and another half days worth of processing, depending on the size of building ofcourse.

DOCARCH

irishmover wrote: »

As I Surveyor, I am not impressed!..................

Them's were the days! :P We did not even have a computer in the office back then!!! :eek: All pen, paper and drawing boards. Hard to believe...but true.

Don't worry, if I was presented with the same task today, I'd run a mile/call my friendly surveyor.

One other point, on smaller buildings/houses, in doing the survey yourself, you get a really good understanding of how the building/house 'works' which is invaluable when proposing/designing alterations, extension and/or the refurbishment of that structure.

irishmover

DOCARCH wrote: »

Them's were the days! :P We did not even have a computer in the office back then!!! :eek: All pen, paper and drawing boards. Hard to believe...but true.

Don't worry, if I was presented with the same task today, I'd run a mile/call my friendly surveyor.

One other point, on smaller buildings/houses, in doing the survey yourself, you get a really good understanding of how the building/house 'works' which is invaluable when proposing/designing alterations, extension and/or the refurbishment of that structure.

Take a look at this

Now imagine it being your whole house!

shane6977

Hi Irishmover,

The proposal for having the 3d survey done got knocked on the head as there was no appetite for having the whole building surveyed (even though it's badly needed) and we have been told to use the as-built drawings we have on file (even though they're nowhere near accurate). Looks like we'll be running around cross checking everything with tape measures, pen and paper!!

I can't see the image you posted, any chance you could repost?

irishmover

http://www.youtube.com/watch?v=6Y-9--KI8NY

That any better?

Yeh... That's a shame about having to use pen, paper and a measuring tape! Though to get people on board

rumour

I'm in France and want to get a survey done of a property 7 hectares with some old buildings. I'm looking for a terrain map and a detailed survey of the house.I note above the issue with things not being plumb square etc but this is exactly what has to be established.At some poont the survey will have to be turned into a digital output for pricing, but the baseline survey is the starting point.
The terrain survey is simple(well maybe not lots of trees) and the house is peculiar to say the least, extensive cellars going into the hillside etc.

Can any of you recommend how to move forward and do any of you have any idea of how much this would cost?

Supertech

Is the survey in France or in Ireland ? Difficult to estimate cost without location, and in either case you should try to get quotes from at least three surveyors with this kind of experience. Contact the Irish Institution of Surveyors www.irish-surveyors.ie if in Ireland and look for qualified surveyors in your area. Not sure what the equivalent body is in France, but that information should be readily available over there.

Essentially there's two different types of survey involved in what you're trying to do - a land survey and a measured building survey. Both can be tied together to give an overall picture of how the buildings sit in the terrain, with laser scanners used internally and externally on predefined survey points to correlate the interior and exterior. I don't have huge experience with laser scanning, but I think it's a relatively straight forward job when carried out by an experienced practitioner. The extensive trees may make the land survey a bit of a slog as they can be a considerable obstruction for GPS kit. In Ireland, LIDAR information is available from OSI which gives basic topographic information, but accuracy may not be at the levels you require. I'd guess that similar data may also be available in other jurisdictions.

Modern survey data collection software can export your data in numerous formats and it can then be output either as traditional 2D CAD drawings or as more detailed BIM models. so you're on the right track saying that the baseline survey is the starting point. The better this is the more information you'll have as the project progresses.

Bear in mind as well that as you begin to produce drawings for pricing, unless your consultant is using BIM, a lot of the detail regarding the walls being plumb and square etc. will be lost in the 2D translation, and if 2D drawings is what you're after, it might be more economical to get a traditional measured survey done rather than a laser scan.