ShrinkWrap and effect on texture mapping a jpg from an obj export

Rhino Rhino for Windows
1

Hi,
V5 and 8
When I get V8 setup (and I hope I can get started with it, see other post) to open V5 files. I am keen to try out ShrinkWrap.

My existing workflow is:-
export obj from Photogrammetry (Agisoft Standard), one gets a .obj, .jpg and .mtl
file import the obj into Rhino, then when still selected go properties > oil paint tube icon, allocate texture, alter by layer to by object.
in shaded view, setObjectDisplayMode and choose rendered
get a very realistic looking model.
repeat that last command for all viewports.

Now if I were to ShrinkWrap my mesh, should I do so before or after doing the texture application ?

How does Rhino know where to map the texture to, is it in the .mtl file all the secret ingredients on what pixel goes where ?
If its then presented with a shrinkwrap, will it still manage that ?

To be able to work with a smooth item with a quality image and get nice sections and non jaggy form to work with is eagerly awaited, but if no image gets mapped, then I cant start to even use it, as I have to go by visual features on the existing photogrammetry object.

Cheers

Steve

2

Before. Shrinkwrap is a disruptive operation. Texture mapping won’t survive it.

— Dale

3

Hi Dale, Thanks.
Just how does Rhino know where to place a texture jpg generated during export as .obj from a photogrammjetry object ?

A vase is one thing, a complex brake assembly area on a WW2 bomb trolley is something else !

It manages it normally, is there some kind of mapping file it refers to ?

I am intrigued and also worried how a shrinkwrap would be seen in this process.

Cheers

Steve

4

The scan mesh will have a UV layout that generally looks like a ton of separate scattered islands in the UV editor. This mapping info is how any texture in an assigned material will get applied to the scan mesh. When you export that same mesh object as OBJ format, the UVs will go along for the ride.

When you Shrinkwrap the scan mesh you are making a new mesh object that will need it’s own UVs. If the scan mesh had one material applied, you can use it as the custom mapping object for the shrinkwrap mesh and apply the same material.

5

Hi,
Not sure I understood some of that.
I guess I will find out when I open a file from V5 with its mapped texture into V8, and shrinkwrap it then do as before, apply texture by object and browse to the texture again, see what happens.
New to meshes, and as long as the texture appeared was not in needing to look under the bonnet.

any videos on photogrammetry texture mapping welcome. and on real world use of Shrinkmap.

Steve

6

Upload a simple sample file of a scan that shows color data in a texture map and I can take a look.

7

Hi,
Will do,
what is the method for upload, just the usual image or file upload tool 7th tool from left ?
It might be too big for that.
What are the rules and options on file size etc ?

Steve

8

if it is too big to upload here, use this link and post back here if you posted