3D Scanning

[Sketchrender]

Morning

 

As I have the Autodesk Premium suite, and it comes with a shed load of software, has anybody worked out a way of 3D scanning sites, and pointcloud loading it up to work with real world scans as opposed to measured survey.

 

What are the options from Cheap to Expensive.

I am a one man band company, and work on a lot of old building, and big sites generally.

 

Thank you

 

Phil

[Jonathan]

Photogrammetry has many uses and is ideal for old buildings. Really depends on the required resolution and project scope, sometimes laser scanning is the only way. I use Agisoft Photoscan regularly which is cheap and quite powerful. Here's my last photogrammetry project: http://pixogram.co.uk/?p=1729 The site took an hour to photograph and a few days to process, retopologise and clean-up. There's always clean-up, Mudbox is fine but ZBrush better.

[Darawork]

I've always liked the look of these: http://www.faro.com/en-us/products/3d-surveying/faro-focus3d/overview

 

 

You can rent them out, have a search.

[Noise]

What Jonathan mentioned above is bang on. Photogrammetry (technically known as Structure from Motion) is the most cost effective way of doing it. Once you have the 3D model created (Agisoft is what I recommend also but not the only software) you will need to optimise the model or retopogolise it. Basically this is the process of tracing it in 3D so that you have clean - efficient geometry. It is not essential to shoot separate textures for this as you can project the textures from the photogrammetry model onto the retopogolised model.

 

At the other end of the scale is a Faro/Leica 3D scanner ("phased based" are quicker and more accurate than "time of flight") which will provide you with a very accurate point cloud but will cost alot in rental of the equipment and will require someone to operate them. You will also have to do the 3D retopo yourself and photograph the textures for a good result. Another point is that there is alot of additional equipment that Faro/Leica provide that can cost a small fortune and do specific and important things that are necessary for the scan. In short, it is a technical and relatively complex process that should be left to those who know what they are doing and have the money to provide the equipment to do it properly.

 

Three important points;

1. The most important question you need to ask is what Jonathan mentioned above - "depends on the required resolution and project scope". This will determine the equipment you need to capture the scan.

2. If you are going to hire some of this equipment, it will cost a fortune. Seriously, sometimes you have to put down a deposit to half the value of the scanner - Leica and Faros of this spec can cost 60k.

3. And back to reality - basically, get your DSLR and go out and do some tests. Initially, use something like 123D Catch if you haven't already to create the model. You will soon understand the parameters of how to shoot buildings of various sizes. Use manual settings and I would recommend measuring key aspects of the building so that you can scale it in Max.

[RyderSK]

I am extremely impressed by those FARO videos.

 

I currently toy around with Agisoft using my NikonD800 and 50mm primes, I only intend to use it on small items (like furnishing, not houses or sites). I understand it might absolutely lack the precision of laser scanning, but on other hand, the detail is quite impressive due to 36MP chip on that camera and I can just zoom to intricate details to capture. And then there's of course, the texture.

 

Hmm, I'll browse that site later.

 

Really nice work Jonathan ! I am actually impressed as well that you captured whole smaller site with regular DSLR/Agisoft combo. Why do you Zbrush better ? I have them both, I suck at both :- D But I find Mudbox slightly more comfortable for retopology to my liking and the "auto" retopo seems quite identical between them now ? I still use Zbrush decimator to crush the model afterwards, I love how that works.

Edited April 3, 2014 by RyderSK

[Jonathan]

Im certainly no expert with ZBrush or Mudbox but ZBrush's new ZRemesher tool looks, ( I havent used it yet), awesome and completely automatic?. Often photogrammetry is seen as the poor cousin of laser scanning, I disagree, photogrammetry is so versatile and flexible it still amazes me what can be done. Pioneers of photogrammetry, check XRez Studio's testing of Autodesk's ReCap: http://vimeo.com/84819306

[RyderSK]

Mudbox 2014+ (with servise pack) or 2015 has "one button" automatic retopology as well. Actually they had it 2 weeks earlier compared to Zbrush :- ) They seems to work pretty much the same to me.

Thanks for the link, I'll check that.

[DaveC]

There are pros and cons to each approach really.

 

To do either well is obviously going to cost in time/processing.

 

 

The main issues with photogrammetry really are glossy items and lighting.

 

Getting a wet day might cause issues if you have lots of already smooth flat surfaces that need capturing and you have no way to get higher aspect imagery (go rent a cherry picker haha)

 

A dark/gloomy day is also not ideal as it means higher ISO = noise or long shutter speeds which might mean blur. So you're on a tripod = taking longer still.

 

Then again a sunny day may not be ideal as shadows get baked into the models textures, which you may not want and need to remove etc.

Also on a sunny day you get more specular reflections which again are problems for photogrammetry.

 

 

This isn't to say photogrammetry isn't good. It covers loads of weaknesses/gaps of laser scanners, along with being cheaper mainly due to the equipment costs being lower.

 

It's been around decades and has always had a place in certain areas of industry over laser scanning techniques.

 

 

 

All said the time spent on travel, on site, dealing with issues, and processing, are probably quite similar irrespective of how you capture the data.

 

It's all about working out what you want to capture, then pick the tools that do it the best at the lowest cost.

 

Photogrammetry has probably seen the biggest boosts in recent times due to cheaper cameras and faster processing speeds of computers... but to do good professional level photogrammetry that someone will pay you money for will still be expensive.

 

 

All my 'tests' are evidence of that haha... they only come out well when you invest serious time with the tripod, images at elevated positions etc... it can start to get expensive hiring those cherry pickers haha!

 

Dave