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Tema: Deep Dream’s Caustics

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    Apr 2002

    Deep Dream’s Caustics

    Deep Dream’s Caustics
    by Dan Tabonet

    When I was an 8 year old kid, some of my young friends used to collect mysterious things in water ponds near my home. I'll always remember the day when, for the first time, I could see what was so exciting to them: thousands of very little, very shiny thunderbolt creatures in a so little flasque of water they showed to my wide open eyes! It was so amazing that I saw myself at the size of one of them, swimming among them... and that was the dream! So, since that day I have asked myself how to share this.

    Many years passed before I saw one of the first 3D software packages in early 1993; it was Sculpt Animate4d on the Amiga platform. That was a kind of revelation - and a challenge: making others see my dream! But at this time modeling a single chess piece and making it turn on itself was a "piece" of work, since rendering one frame at 640X480 resolution could take half an hour!

    However, when more sophisticated software came for my needs of modelling insects, I trained a lot with my dream still in mind. And believe me, that kind of modeling was much more complicated than making space vessels. Just have a look, for instance, at the images in the 12 volumes of the Larousse Encyclopedía of Insects and you will be convinced that imagination is nothing compared to the real world, because it is in a real brain: yours! That was an artistic but very technical challenge as well. So if I had a word to future animators who hesitate to show their work, my motto to you is:

    • Observe from nature
    • Learn from nature
    • Modestly imitate, and you will go where no one has gone before where dreams get real (appearance)...

    Technical Details
    Talking about all the "making of" the movie would take too long to explain in detail. Some examples of amount of work, for now: 14 months of perfecting the model more or less 250 times for a finally -compressed- .blend file of 73 Mb including 555 meshes, 906 595 polygons, 107 Mb of textures... you begin to see the challenge and the drastic choices I had to make for the final render, and that taught me precious things:

    For instance, I now get a better flow of production because I lost a lot of time scaling and positioning the new meshes in the scene instead of creating them by the means of temporary reference boxes (simple cubes created where I projected to make new objects later)in the scene, exporting these boxes out of the scene and modelling into them the new objects separately,finally introducing the real new objects after wards into the scene.

    Another precious hint I learned when I made my movie is that all objects that came out off the came out off the camera field had to be hidden in layers by the means of layer keys, to make the render be possible on one machine in a "reasonable" time. For the same reason I had to turn raytracing off and use only shadow map lights. That increased the render speed a lot, but there was a serious problem to keep realism: for reflections of underwater scenes I had to find something to produce caustics. These are animated, random wavelets of light made by refraction on the water surface that you can see under it. This phenomenon is hard to produce in 3d, but very common in nature. If I wanted to recreate underwater ambiance, I couldn't do without it. So when I discovered the excellent free software, Caustics Generator, that convinced me to faq caustics.

    Now let's see how it works to make a relatively realistic underwater scene environment. In this little tutorial we assume basic knowledge of the Blender interface.

    First the scene lighting.
    You need 3 lamps:

    • "Projector lamp": First of all, add a spotlight in a clear 3d window in Blender, and turn it more or less downwards. Set the spot as a Buffered- shadow, then in a classic-halfway toggle, then the spotbias angle more than 0.5, to soften the border, and make it halo.
    • "Software lamp": Add another lamp (Hemi type) pointing behind the camera, and parented to it. Set its power to a high level, more or less 2. You'll see why we use this lamp later
    • "Darkening lamp": Add Área lamp(s) set to negative power 0.5 or less, positioned upon the details to hide from view. This kind of lamp will darken unnecessary parts of the scene, hiding them from view.

    To make the ground,add a plane in the top view and scale it until its borders are out the camera's field of view. Set the world colors to black. You should see something like this (figure1). (saustics001.blend)

    Now it's time to prepare our animated caustics sequence of images or movie that we'll use as a texture for the projection lamp in Blender. So, first launch Caustics Generator and set the parameters like those in figure 2 (For now these settings would NOT be changed. Later on you will be able to rapidly test different other settings but if you chek the automatic preview, be careful before this to disable antialiasing by setting Supersamples to 10 and Motionblur to 1, otherwise drawings would be drawn very slowly). Then, after setting the directory where you store the sequence of .bmp images, chek Save Output and clik Render Animation.

    Here we are: A complete tileable cyclic animation of caustics, now fully useable in blender on the "projector lamp". But we should use it with care, to avoid some artifacts, because tiled textures can easily appear as artificial to our eyes. Let's return to Blender.

    Our scene opened, let's select the projector lamp and add a texture to it. Next go to the Textures panel and set it like in figure 3. This indicates that the sequence used contains 32 frames (the parameter determined in CausticsGenerator), each of them used one by one and repeated cyclically in time forever. But at this point no control of the size of the pattern used is possible. We have to fix it.

    A smart method is to put a plane under the ground and name it REF, for instance. The only thing to do is to enter Lamp buttons >>Textures and Input, chek the Object box, and enter the same name in this field: REF. Now,the mapping of that textured lamp will adapt to the size and position of the object named REF, like in figure4 (caustics002.blend).

    You should now be able to test rendering. After this, press F12.

    If the patterns of the caustics are too large, you only need to resize the plane object you named REF in lower dimensions, and if they are too small make your REF object bigger. It's that simple! Now, with the REF plane selected, insert a loc key. Then go, say, 100 frames later and slightly move (horizontally only) the REF plane a little. Insert a second loc key on it. You have simulated the effect of the wind on the waves, making the caustics drift along with it.

    Let's push the Anim button and start testing... Good blending, and don't sinque too much in it

    Lamp Settings

    by Dan Tabonet
    Miniaturas adjuntadas Miniaturas adjuntadas Deep Dream’s Caustics-1.jpg   Deep Dream’s Caustics-2.jpg   Deep Dream’s Caustics-3.jpg   Deep Dream’s Caustics-4.jpg  

    Deep Dream’s Caustics-5.jpg   Deep Dream’s Caustics-6.jpg   Deep Dream’s Caustics-7.jpg   Deep Dream’s Caustics-8.jpg  

    Deep Dream’s Caustics-9.jpg   Deep Dream’s Caustics-10.jpg  
    Si vas a subir un trabajo al foro, hazlo adjuntando la imagen, archivo, vídeo o lo que sea, no publicando enlaces de otros sitios.

    |Agradecer cuando alguien te ayuda es de ser agradecido|

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