Complicated model - how to approach?


#1

I apologize if I posted this in the wrong place.

I’m pretty new to 3D modelling, and recently I’ve been assigned a project for work that is unlike anything I’ve ever done, and I have no idea how to approach it. It’s a sculpture that my company will build, and it will be 30 feet tall and made of perforated aluminum sheets attached to an internal pole and frame. The artist has given me a 5 foot tall prototype made of welded metal. It’s sort of a cubist-looking thing, and every tack I try to take just leads to more headache.

Does anyone have any advice or experience with anything like this? I’m sort of freaking out, as I’ve got a rather brutal deadline. I’ve attached a photo.

My apologies for my first post being a “help me” post, I just don’t know where to turn for this sort of thing.


#2

Probably best to scan it.

There are some apps for phone/tablet that are passable but you can get hold of a hand held laser scanner anywhere from £100 to (very expensive!).

I used to have a David Laserscanner http://www.david-3d.com/en/support/downloads

If you need a good sense of accuracy it’s really the only way, we do the same thing in work. It’s what they do to get the clay models into CATIA

1/4 size

Depending on how tight the deadline is, try out a few of the apps first, if they are not free they are cheap. Then if possible see if you can rent a scanner from somebody or maybe get some help. If you have a bit longer and you think you may need one again,maybe look at buying one or if you are inventive make your own (see instructions on you tube).


#3

That makes sense. I’ll definitely have it scanned. Thank you so much for the reply!


#4

Scanning would be best…but if you really had to go manual, I would get a bunch of angles on this and use photomatch. It might be helpful to add a number of reference markers (sticks, horizontal and vertical) plus a few key measurements…good luck.


#5

Search for Photogrammetry and you’ll find a lot. Here is an example…


#6

Excellent suggestion for this and sounds like it could be free too? I had dabbled with Microsoft’s Photosynth a while back but it’s been discontinued.


#7

Why create a 3d model?
You already have a real 3d model prototype…Take advantage of that!

Wouldn’t be better to take pictures of the prototype and use Photoshop to composite it with a picture of the Site?

I myself have not used Photogrammetry and from what I see in the video it is very complicated process, especially for shiny objects so if I was you I would save time by using Photoshop. And, if done right you might get much better results than any virtual 3d model.

Cheers! :smiley:


#8

When it comes to fabrication, I can’t see how something in Photoshop will be more useful for taking measurements than an actual 3D model.

I don’t think OP wants some imagery to show the model in site, but rather a working model so they can actually construct it, therefore accuracy is key in the capture process, whatever method they use.


#9

I always forget the name of the affordable laser scanner that attaches to an iPad and can convert to a 3D mesh…

BTW, I rather like the sculpture. It has somehow an origami feel. Good luck with the project!


#10

@Anssi this one probably https://store.structure.io/store


#11

Yes, that was it.


#12

Oh good to see, I only remember it from kickstarter when my last job wrote about it, didn’t know it was at market already!!


#13

Those little scanners are great! We used one in the office to scan my head!


#14

Thank you all so much for the suggestions!

I’ve requested quotes from local companies about having it laser scanned. In the meantime, I’m in the process of seeing what I can get out of Agisoft Photoscan, although I imagine laser is far more accurate than photogrammetry, especially considering the shininess of the sculpture. I don’t have an iPad, but I may look into getting one of those anyway and borrowing someone’s ipad (or just getting the standalone sensor and following the instructions to get it to work with Android).

I’ll let you know how the photogrammetry and/or laser scanning works out and what the final product looks like!


#15

Great, just a tip. If possible cover the sculpture surface in something that’s non reflective, some matte card perhaps cut to size.


#16

I’m not entirely sure scanning with say a structure sensor is more accurate than photogrammetry. I use both the structure sensor and agisoft photosscan pro. They are 2 different animals really, the scanning resolution of the structure sensor is middling to low and more suited to room scale surfaces, although when textured the resulting scan looks very good but the underlying geometry in quite ‘interpolated’.
Geometry generated from agisoft is very detailed but it all depends on the method of source imagery, from looking at your sculpture I’d say the approach would need to be carefully thought out to capture the angles with sufficient overlap between images. Some of the item models I ha r seen are excellent.
There is a free trial of photoscan available, so it’s worth doing a test. For both methods, as Liam says, reflective surfaces = bad, so you’ll have to do something about that. If you know someone with a structure sensor and skanect it would also be worth a shot.


#17

It all depends on the scanner fidelity really. You want to get hold of a real laser scanner rather than a structured light scanner but a professional laser scanner is going to have accuracy that photogrammetry cannot match.

I have seen ones like this in work:

You can scan a full vehicle straight into CATIA. They are expensive so not possible to buy for this task but you can probably rent them/have somebody come out and scan for you with something similar to this, its the same price as a high end drone for example.


#18

Yeah! That’ll do it.


#19

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