Hi Umang,
If I understand correctly, the core of your proposal is to automatically generate an image preview based on an X3D or COLLADA file. I'm not familiar with those formats, so there's one big question that needs to be answered in your proposal: will the image be generated with the camera being placed in a useful point of view?
Thus, I'd like you to check the following and use the findings to improve your proposal:
- Does X3D or COLLADA embed a preview image as part of the file itself? If yes, then that's probably the image we should be using.
- Do X3D and COLLADA files always contain camera information? If they only contain the geometry (and textures?) of the models, then we're probably going to have an issue with picking a default camera position.
Also, another question that needs to be answered is whether textures are embedded in these files or if they are referenced. If they are referenced instead of being embedded, then texture support in itself would be a complex matter (how would people upload the images needed as textures?), and your proposal makes no mention of it at the moment.
For me these questions are really what makes or breaks this proposal. If the images we generate end up being often from weird angles, or without textures, it will be of little use to people looking at the content on Commons. It definitely wouldn't answer the use cases you've written.
If there is no camera angle information in the files, then maybe the solution is to generate a preview image that contains more than one automatic angle (6 points of views, maybe? the faces of a cube surrounding the model). I think it's something you can figure out ahead of time, at this stage of the process.
At any rate, I think the camera and texture questions need to be researched in your proposal so that we get a better idea of how difficult the task is going to be and how likely you will be to complete something in the given time.