Hi shokan - all those SketchUp files you are talking about are constructed out of polygon data.

MoI is focused on modeling with a different technology than that, objects in MoI are made out of what are called NURBS surfaces. They're kind of like stretchy pieces of rubber or something like that, they're actually mathematically smooth entities.

Polygon data is a fundamentally different way of structuring a model - instead of having smooth surface sheets a polygon model approximates a smooth surface by using a large number of triangle facets.

So for example a sphere in SKP format is not actually a true sphere, it's a bunch of little triangular faces arranged in a way to approximate a sphere. In MoI a sphere is actually a single sphere spline surface.

This difference in the way that objects are structured means that you cannot directly import polygon data into MoI.

You can produce polygon data to export from MoI - what will happen in that case is that MoI will generate polygons from its NURBS surfaces by dicing the large smooth surface sheets up into smaller facet pieces.

But it is not very easy to start with small facets and then reassemble large surfaces from that automaticaly - it's kind of like how you can start with apples and then smash them up to produce applesauce, but if you start with applesauce it is difficult to turn that back into whole apples again.


> I have not used it yet, but can you give me some ideas
> about its use with moi3d for constructing 3d buildings from
> photos? ie, with basic geometry produced by Photomodeler,
> can moi3d then be used to flesh it out?

Well, what kind of data does Photomodeler produce - does it produce polygon models?

One thing to realize is that "3D" is not just one single technology - there are a variety of different ways to represent 3D models and different programs can use different methods for it.


One thing you can do for bringing in a polygon model scaffolding in MoI is to use the program here: http://moi3d.com/wiki/Resources#Obj23dmWireframe_converter

That can convert a polygon OBJ file into a 3DM file that can be loaded into MoI, where the edges of each face in the polygon data become line segments in the 3DM file. So it will just be a set of wireframe lines when imported into MoI but you can use that to snap on to if you wanted to use the model as a reference point or something like that.

- Michael

Hi shokan, so anyway to summarize:

You can't import polygon data into MoI, MoI only works with NURBS data within its own modeling environment.

You can _export_ polygon data out of MoI though, it will convert the NURBS data into polygon data when you export to a polygon mesh format like OBJ, LWO or STL.

- Michael

Thanks very much. Very good explanation. I understood everything.

Here are excerpts from Photomodeler Lite Help:

"Export
PhotoModeler can export the following types of data from the project: 3D Points, Point IDs, 3D Lines, 3D Faces, Surface Draw, and Cylinders. Not all file formats can support all these types. The various export data types will enable or disable based on the Export Type selected and what that format can support. Note that in PhotoModeler Surface Elements are equivalent to 3D Faces in the export.

Export Type
The Export Type drop down list specifies which type file format to export. Currently supported types in Lite are: Autodesk 3D DXF, VRML 2.0 and Autodesk 3D Studio (3DS).

Copyright 1999 Eos Systems Inc."


Any suggestion on what to use then?

Thanks.

Hi shokan,

> Any suggestion on what to use then?

Unfortunately none of those formats will open in MoI, they are all polygon data formats.

There are free NURBS models on the internet but they are scattered in smaller libraries, it's just a matter of finding them.

Here's one with architectural models that will open in MoI, just download the 'free Rhino NURBS model' and not the 3ds version.

http://www.flyingarchitecture.com/



Cheers

Hi shokan, yeah so like Danny mentions those are all polygon data formats.

What is it that you want to do with the model when you import it into MoI?

If you want to use it as a kind of drawing reference, you can get it into MoI as a bunch of lines by exporting from Photomodeler to one of those formats (probably try DXF first), then convert that into an OBJ file using one of the polygon format conversion programs out there (here's one called 3DWin: http://www.tb-software.com/products_2.html ), then use the OBJ to 3DM wireframe converter from here: http://moi3d.com/wiki/Resources#Obj23dmWireframe_converter . That will convert the OBJ file into a 3DM file with lines in it, and you can open that 3DM file in MoI.

But if the idea is that you want to arrange a scene with some premade props in it or something like that, that probably means you are going to be using a rendering program to generate the final image and if that's the case you most likely should try loading those objects into your rendering program instead of trying to load them into MoI.

- Michael

No, the first thing you mentioned. I just want a blocky version of the building made from PhotoModeler with key dimensions and some design elements in the right places using photogrammetry. So, the workflow will be PhotoModeler DXF to OBJ and then to 3DM using your utility. In MoI, I plan to assemble some architectural detail models made in MoI beforehand (brackets, doors, windows... all Victorian stuff) and stick em on the base model, and also alter the base model as I see fit. I don't see any problems. Any suggestions?

Hi shokan, yes so that method could work for that kind of use.

So the reason why DXF may be preferable is that the 3D Face entities in DXF files can be either 3 or 4 sided, while the 3DS format (and I forget about VRML) can only contain triangle polygons.

So if Photomodeler is producing things like boxes those will be a bit cleaner with 4-sided polygons if possible.

Then after the conversion steps, you'll have a 3DM file to bring into MoI, and to create surfaces you can select 4 edges in a loop and use the Construct > Planar command to build a planar surface through them. Then after building up planar surfaces you can select them and use the Join command to join them into a solid.

- Michael