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syntropic

shadows confusing me...

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  • Hi!

    I am trying to render a still scene.... One issue I cannot seem to resolve is what appears to be uniform area of shadows on the floor of this scene covering the entire floor and about 1 foot deep (per approximate scale of the room). I have attached the image. It is a work in progress, so just FYI I am sure there are other problems (like relative scale of the various items for one). The render I am attaching is still not lit properly, but before I start playing with the lights, I want to figure out this shadow problem.

    Quick light inventory....The lights I have in this scene are as follows: 8 tubes covered with luminant material in the fixtures. One omni light in each fixture (around 75% intensity per light), two spotlights going into this room from behind the camera, and two area lights-- one on each side of the room near the floor (these are also fairly dim). Lastly, I have an infinite light several thousand cm away, but I am not rendering it (was trying to see if I could get a better render with it, but I think I am going to keep it out); the red stop light is on for both editor and render.

    The aforementioned spotlights (the two behind the camera) and the area lights do not have shadows enabled. The only shadows which are enabled, and which I expect to see should be coming from the omni lights in the fixtures. The infinite light again is not being rendered but is still in my object manager (with two red stoplights).

    But this puzzles me for another reason....I have seen still scenes done by others (much more professional, I might add), and I often see items with two red stoplights (editor and render) in the scene (typically lights or other light related items), and up until now, I just assumed they were superfluous items--perhaps left over from when the scene was being modeled. I am thinking perhaps that maybe I was wrong to assume this... that maybe some of these items that are not rendered still have an affect on the scene.

    If anyone can suggest where these shadows are originating from -- and also clear up whether items not rendered affect a scene or not -- I would be very appreciative.

    Thanks!

    Paulpost-88497-036424800 1278263823_thumb.jp

    NB: I forgot to add. I am rendering this particular still using VRay. I am pretty green with Vray, so perhaps that might be part of the problem.

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    I just did a quick test inside a cube with a single lightsource, with autolight off. If I disable rendering the light it's completely black, so there doesn't appear to be a residual effect.

    Steve

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  • thanks roken.... whatever I am suggesting with non-rendered items is something more subtle. For instance, you can turn on red stoplights, but if you still have the green check mark, the item is still generating instances or other things, so I do know that "not rendered" does not equal "deleted from scene".

    In another scene I found... I saw a rather ingenious idea... although again, it confuses me. The creator of the scene put 5 or 6 primitives textured with a chrome material in the middle of the scene. These items were also not rendered, but I have a hard time believing that this was just some extra item which wasn't deleted. The scene in question was an interior shot with only one window, and logic would say that having randomly shaped chrome objects would give your "diffusion bounces" more bang for the buck.

    I wish I could get the dirt on this matter. It is strange for me to work in an application which because of its niche and market share still has a few question marks when it comes to how things interact in a scene.

    I am still playing with the lights in this scene, and I am sure eventually I will figure out what is causing the room to be flooded with that ungodly "fog" on the floor.

    But, while I have this picture posted (above), one problem I do seem to have all around is scale. Does anyone know where I can find a tuturial on how to set up scale from the begininng so that it is all object are accurate relative to one another?? Again, creating stills is new to me, and I typically just start throwing objects I create (or find and modify/texture) into a scene and then scale them just using my eye. But this doesn't seem to be the best approach. For instance, in this photo, you have the distance D of the camera to the back wall, and H, height of the back wall.... I would like to know how I can use this data to fix a scale (meaning if D is 15 feet, and H is 12 feet, how big do I make say a 2-foot object that happens to be in the middle of the room (like the shopping cart).

    What I do not like about this scene is that the bench-chairs, look OK relative to the wall, and so does the newspaper box.... but the two do not look good relative to one another. Similarly, the cigarette machine looks too big, yet it is approximately correct according to the scale of the chairs and newspaper box.

    Any help is appreciated...!

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    Can't help regarding the lighting, but if you're using Vray then the scale issue is simple: build all your objects to real-world scale, including the room structure itself. That is, if the object is 3 feet high, make it three feet high in the scene. You can use whatever units you like - if you choose inches, your 3-foot object would be 36 inches high, same for any other units. I use centimetres as the scene unit, but it's not required. If you do that, the scale problems are eliminated. All you have to do then is somehow obtain the correct measurements for the objects you're modelling (and yes, sometimes you do just have to guess them!).

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  • thank you spedler. I have never paid much attention to that. But I have heard that Vray is quite sensitive to unit/size consistency, so I am going to have to back and guess all my sizes and let inch = centimeter (since that is what I am using as well).

    This actually brings up a quick question -- is there a plugin which quickly/easily measures distance between two points. I know there is the measurement & construction option under functions, but I have tried to use it -- and not only did it seem a bit confusing, but I was left with random measurements all over my scene, and no way (at least not in the help) to get rid of them.

    I think I may have found the problem to my shadowing -- I have to wait for a render which is currently underway -- but I had "enable near clipping" under camera ticked on and from what I read, that may be the culprit. If not, I will deconstruct my scene again.

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    Hi Syntropic

    With regards to measure and construct, 3DKiwi did an excellent tutorial on this a couple of months back, definitely cleared things up for me.

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  • cool... will look at that.

    I just got done watching his bodypaint export uv map to photoshop, and while it still left me with a lot of question, it was the first tutorial of its kind -- anywhere (and I include black market tutorial sources) on the net.

    I can see the value in getting adept or skilled in one or many areas in Cinema 4D and then doing tutorials, for post either here at C4Dcafe or for ones own blog (or both)....

    Given the rise of popularity of C4D (there a local group here in Chicago has doubled to something like 80 people in less than a year), coupled with the dearth of quality tutorials (understandable, enthusiastic, & boring anglican accented english (no slur intended)), I can see such an undertaking to be a traffic gold mine.

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