It's funny how things in academia are rarely ever heard about even if they are incredibly novel and interesting. I think it's because of their limited application, especially in the artistic rendering world. (Of course, it also includes the inability of most academics to commercialize so they rarely make it to press.)
A master's thesis from 2001 describes a wonderful way of animating Chinese landscape paintings and panoramas in order to create a three-dimensional walk through. Their method uses image based modeling and rendering (IBMR) and improves on a previous method called Tour in Picture (TIP). Their method is multi-perspective TIP and fixes many of the disadvantages of regular TIP. The main disadvantage of regular TIP was the short animation times. With multi-perspective TIP the animation times can be much larger. In fact, TIP animations were generally ten seconds in length but the animation on their research page is one minute and thirty seconds. (IBMR is not one of my areas of interest so I'm unable to summarize their method but they have very pretty results.)
I highly recommend you check out their video section. They really are able to create pseudo three-dimensional models of the scene that can be walked into (ie: they have depth) and through.
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NPR Line Drawings Really Work!
A new study by Forrester Cole, et al. titled, "How Well Do Line Drawings Depict Shape" presented at SIGGRAPH 2009 evaluates the methods of producing line drawings developed in the past few years (which are quite comprehensive and what Forrester Cole seems to have devoted his entire graduate and PhD Student career to, so let's thank him).
In their study they had participants orient what are called gauges onto line drawings of 3D objects. Each guage is a disc with a line that represents its normal. Participants had to orient the normal of each gauge. A correct disc orientation would make it look like the disc was actually on the surface at its position. The position of each gauge was fixed and each gauge was initially superimposed over the model so as to not cue the participant. The gauges also did not interact with the models.
The study compares six different styles of rendering. Among these six styles were fully shaded images, apparent ridges, suggestive contours and an artists line drawing of the same object (the authors note that plain contours were rendered over all models other than the artist's image).
Their results are quite long and detailed and take up a majority of their paper. They show that shaded images are the best for depicting shape, however, that was an expected hypothesis and not the point of the experiment. In summary, their data shows that each line drawing method has its own strengths and weaknesses. Most were comparable and at times better than an artist's drawing. Some methods are good for some types of models while other methods are good for other types of models.
This is good news for NPR but I still want to see these methods developed into something that doesn't bog down processing and destroy interactive frame rates. Albeit, some methods achieve interactive frame rates (30-60fps, but sometimes they quote interactive frame rates as 5fps) these methods are still unsuitable for real-time environments such as games and walk-throughs that are not prerecorded. Read More!
In their study they had participants orient what are called gauges onto line drawings of 3D objects. Each guage is a disc with a line that represents its normal. Participants had to orient the normal of each gauge. A correct disc orientation would make it look like the disc was actually on the surface at its position. The position of each gauge was fixed and each gauge was initially superimposed over the model so as to not cue the participant. The gauges also did not interact with the models.
The study compares six different styles of rendering. Among these six styles were fully shaded images, apparent ridges, suggestive contours and an artists line drawing of the same object (the authors note that plain contours were rendered over all models other than the artist's image).
Their results are quite long and detailed and take up a majority of their paper. They show that shaded images are the best for depicting shape, however, that was an expected hypothesis and not the point of the experiment. In summary, their data shows that each line drawing method has its own strengths and weaknesses. Most were comparable and at times better than an artist's drawing. Some methods are good for some types of models while other methods are good for other types of models.
This is good news for NPR but I still want to see these methods developed into something that doesn't bog down processing and destroy interactive frame rates. Albeit, some methods achieve interactive frame rates (30-60fps, but sometimes they quote interactive frame rates as 5fps) these methods are still unsuitable for real-time environments such as games and walk-throughs that are not prerecorded. Read More!
