3D scanning of building facades

[Jimmern]

We've recently used a service to 3D laser scan the facade of a historical building which we are going to design an addition to here in Oslo.

We asked GeoSurvey to scan the facade using a Leica Scanstation 2. This produced a 3D point cloud consisting of millions of points. The scans are made in many passes from different viewpoints and then registered and sewn together to remove stray noise or unwanted obstacles (cars, streetcars, people) from the various scans. The resulting 'cleaned up' point cloud has an average point density of 1 point / 10 mm. Even on this small building it's pretty massive.

The real trick is of course getting a 'usable' 3D model out of the cloud. GeoSurvey will further manipulate the data to give us a triangulated surface model which we can have as a reference for the "existing" condition of the building. I'm pretty much counting on having to model over it (like 3D tracing paper) to simplify it and get a truly usable model. They just sent us the first round of data and will make the polygon model in a few weeks.

My previous experiences with 3D scanning have been hit and miss. I used it pretty sucessfully on a museum project when we had problems getting the 3D form smooth enough for our liking. We had a CNC foam model of the form which I then spackled and sanded until satisfied with the form. We borrowed the 3D scanner at the AHO (Oslo Architecture School), a Minolta Vivid
and were able to get a usable polygonal model that was smooth enough for our needs in Schematic Design.

The School of Architecture at UT Austin also has a Minolta Vivid 910 which I was fortunate enough to play (ahem) research with a couple years ago. Scanning was great fun, but the real magic lies in how you use all that data once you've got it in. I had my theory class students doing som exercises in transforming their designs from digital -> analog -> digital again (as discussed in the physical modeling thread) which were pretty interesting, but we didn't have enough time to really put the scanner and 3D printer through their paces.

Never tried this full-scale before, it will be interesting to see how the final result on this one comes out. I'll keep you posted.

Anyone else have any interesting experiences with this technique vs. traditional measuring?

Here are a few images of a reduced version of the point cloud (only 45,000 points). Larger res images here.

[Jimmern]

... and here is a .skp of the reduced data set. Kindof fun to spin around, but otherwise pretty useless.

[ajwtaylor]

Our local authority have produced a 3d model of a large area of Glasgow City Centre, in conjunction with the Glasgow School of Art.

This can be seen here

I attended a couple of days of seminars about its development which was interesting. It covers something like 20sqkm in area all to within an accuracy of 200mm (that was the tender specification, allegedly its more like 60-70mm tolerance).

Clearly this has a variety of uses for the public and professionals alike. The council outlines its objectives as being:

• enhance the understanding of the built environment; assist the regeneration of the City;
• improve the participation and consultation process for future development proposals in the City;
• provide a visual aid to help explain the impact of a development to the public, elected members and developers;
• provide a versatile promotional tool to showcase development in Glasgow;
• and improve the quality of all development on the ground.

YOu can see animations produced from the model here and images here. Though the images page is somewhat typically down at the moment for upgrading.


We received some presentations from the guy who set up Cyark. A truly exciting and innovative organisation with 'Google Politics'

Although i learned a huge amount from this, i have yet to be involved in the use of a laser scanner. U can download point clouds of some World Heritage Sites from Cyark's website and i believe that their intention is to make these publicly available as a means of documenting these places and providing opportunity to understand them from your desk. Interesting.

[-archie-]

A friend uses the Leica HDS3000

[m-suke]

hy..we had also the same technique for the reconstruction of the city hall in Sarajevo,..

"The City Hall is the biggest and the most representative building from the Austro-Hungarian period in Sarajevo. It burnt down in the night of 25th-26th August, 1992...The building was constructed in a mixture of styles combining historicism and pseudo-Moorish styles. The style models are the so-called Mozarab and Moorish arts from Spain and the Maghreb. The basic construction elements are columns, walls, arches and glassed dome roofing the hall"


the facade was scaned fom each side, we had drawings like yours with millions dots in cad, ..,the team who scaned it draw in cad lines over the dots, at the end it was very usefull, we had the existing level and we use it for the new projected facade..

[gorgon]

Interesting thread
and I would expect more from ppb on this particularly in relation to: "how can you do this the homemade way" (without the 3D scanner)

[ALoopingIcon]

Free 3D scanning of building?

Without requiring costly hardware and software?

Yes it is possible.
- Make some nice photos, upload them to the Arc3d service (www.arc3d.be)
- Wait for the result, open it and process it with MeshLab ( meshlab.sourceforge.net )
you can get result as this:




Cheers
P.

[Jimmern]

Arc3D website is interesting, I didn't know about that one.

Photogrammetry is the technique for extracting 3D data from 2D images. The Arc3D seems to be a web app that does the same as Realviz Imagemodeler (which like everything else has been taken over by autodesk). Photogrammetry is definately the poor man's 3D input method of choice - lots of cool examples out there.

The real find of this thread is perhaps Meshlab -- an open source 3D program that deals with high density point clouds. It would seem to be the back-end of the Arc3D site. The great thing is that it's a free downloadable stand alone app. I'm playing with it right now, and it seems pretty cool.

[Miggsy]

arc3d and meshlab -great links, thank you.

[gorgon]

that's what is so amazing about this forum thanks everyone