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ChrisZuckerberg

Trimble RealWorks and SketchUp Pro

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ChrisZuckerberg

Hello everybody !

I'm really new in 3D scanning. I'm using the TRIMBLE TX8 and the post-processing software TRIMBLE REALWORKS 9.0.

My current aim is to modelize a building

As the modeling module of TRW is not so performant, I rather use the the TRIMBLE SCAN EXPLORER module of TRW to transfert edges and some geometrical primitives from TRW to SketchUp in order to use them as guide for my modelization in SketchUp.

The problem now is that:

- the edges extraction is not so sweet as in the youtube vidéos (few number of edges and bad extraction);

- When you succeed to transfer any edge or any geometry, it is not so precise as on the scan image.

- some functionalities of Scan Explorer are not permanent, they change depending you open it directly from TRW or if you do it from SketchUp.

So I'm looking for advises.

thanks !

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Tyke

By definition there are no scan points on an edge, there are many close to the edge but on one of the two planes forming the edge. To get a true edge you have to create the two planes and intersect them. Most scan processing software can create the planes, intersect them and export the resulting edges as geometry. I'm not too sure what TRW 9.0 can do these days as it was TRW 6 that I last used and that's a few years ago.

 

You can load Trimble scan data into other scan processing software and perhaps better create your geometry. Have a look round and get hold of some of the test versions available to see which program best suits your needs.

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ChrisZuckerberg

Thanks Tyke !

I heard about EdgeWise of ClearEdge 3D. But I have not yet succeed to have any free trial.

As I already a TRW licence i thought that it was better for me to do all what is possible to master this software.

But it is not so easy.

As you said TRW allows to create planes, but the problem is to fix their position or to make them follow the point cloud surface (Projection problems).

TRW 9 even allows the user to draw polylines and planes on the point cloud that you can export later in DXF, but the problem still the same (their projection is difficult to do).

I have already modelized a building directly from TRW modelling module, but it took me so much time because of that projection issue of planes.

I'm actually trying to create new frame for each plane to facilitate that projection.

So if you can just get a free trial of TRW 9.0 and look over the software in order to guide me, it would be really kind.

I need advises for an experienced engineer.

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Tyke

What are you scanning? Building externals, building internals, statues, piping systems?

Have a look at the Faro 3D Software, they have a suite of software solutions that work inside AutoCAD (Bricscad etc) or Revit. They have automated and semi automated systems for steelwork, pipework, solids and others. See which best suits your needs and get a test version for free.

 

I'm no longer active in the Trimble software and at the moment I have so much work on I just couldn't start delving into TRW 9.0, much as I would like to do.

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ChrisZuckerberg

Hello Tyke !

I'm actually attempting to model both building internal and external .

Thanks I will check out that Faro 3D software.

hope it will be better.

Another preoccupation is that issue of registration. i'm not yet comfortable with any method of registration. so if i can get for each method the exact steps to follow, it would be great.

And finally please can you tell me something about the scanning for topographical purposes with references points on the site (GNSS points or any topographical point)?

Thanks !

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Tyke

Does TRW still use manual registration? I know that other software have moved to automatic registration. Basically if you are using manual registration you need to match the same points in the various scans, your control points (the spheres, targets or very distinct unique points) can be identified in two scans and 'locked onto each other' and do that for all of the common control points in the two scans. Then move on to the adjacent scan and match the common control points in that scan and the next one. Proceed along until the last scan and if you have done a complete round of the building you can close from the last scan onto a common control point in the first scan. TRW can then calculate the closing error and you must decide if it acceptable or not.

 

Any or all of your control points can be given the coordinates of the coordinate system you are using, or GNSS coordinates, and all of the points in the scan will then become the coordinates of the coordinate system. The earlier versions of TRW could not deal with very large numbers and you had to determine N-S and E-W offsets, perhaps that is no longer an issue in TRW 9.0, I know Trimble were looking into the problem a few years ago but I never heard what they had decided.

 

Are you using the English language version of TRW or another language. I used the German Language version (even though you can swap languages) as everybody else in the office were German and I was the only English native speaker. At that time the TRW help was not too good and we did struggle a bit at the beginning. There is a Trimble forum somewhere from which you could glean some information.

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ChrisZuckerberg

The registration now is supposed to be automatic.

But when I perform it the software ask me to extract targets, fit target ..., what make me confuse.

Sometime automatic registration succeed, sometime it doesn't. But I never know exactly what I did to register my work.

And as I am rather a french speaker, I'm not really comfortable with TRW help which is in English.

 

About the Topographic Survey with 3D scanner laser, I'm asking but the methodology to follow on the field (how to behave on the field, particularly how to take references on target set on a known point) in order to apply a direct georeferencing during the post-processing.

 

Thanks !

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Tyke

The automatic registration can only succeed if you have a high quality scan where the points are relatively close together and sufficient well defined points for the software to recognise them. Low quality scans will be more likely to be unsuccessful and manual registration is in this case also less accurate, as each target or sphere has a smaller number of points on it which makes calculation of the centre point less reliable. You also need to be looking at at least 20% to 30% overlap of the scans to get better results, we always went for a 50% overlap with a point spacing of around 4 mm, which could be seen as going over the top, but we never had registration problems and TRW always automatically found all of the targets. When you consider how quickly the points are observed, up to one million points per SECOND on the Faro 3D scanners, the extra time taken for good overlaps and close point spacing is really negligible. We surveyed the whole of a medieval German castle in three days and that included the geo-referencing of the whole internal and external control points.

 

The geo-referencing of the control points can be done in any of the normal surveying techniques, using GNSS receivers, total stations, etc. This shouldn't be taken lightly and should be left to a qualified surveyor to do the geo-referencing job. After reading in the point cloud data and before starting the registration process you need to go into each individual scan and identify all of the control points that have been geo-referenced, select the properties of the point and enter the coordinates. You don't need to geo-reference every control point, but two on each side of a building would be sufficient if they have significantly different heights/levels. The difference in level is required to give the scan more vertical stability, so to say, to stop it 'toppling over'. We used GNSS receivers to establish a ring of control points on the ground around the building and using these points for resections we then used total stations to define control points in the upper part of the building and through windows into the inside of the building. But you need to explain this to the surveyor if he is unfamiliar with the process. Be careful when using 3D scan data for topographical surveys as the scanner observes the top of any vegetation and hence you have incorrect levels if you use these points as ground level. On hard surfaces the problem is the one you mentioned in your first post, it is difficult to extract accurate edges from the point cloud. I did see some software from Trimble last year that they use for evaluating the point clouds from their mobile scanners used in longitudinal road surveying, it could automatically define edge of carriageway, top and bottom edges of kerbs and walls with no other input from the user than issuing the command and defining the travel line. After talking at some length the Trimble guys they confirmed that this feature was not in TRW and there were no plans to introduce it. Why not? It would be of great assistance when working with point clouds.

 

Good luck.

 

Check out this link to see some examples of another castle we did http://www.cadtutor.net/forum/showthread.php?90635-How-to-survey-a-crooked-house/page2

Edited by Tyke
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