By: Ahui Herrera [3]

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Step 3:
Rendering the 3D Model

There are two basic concepts in creating the illusion of movement. One can either move the object in question a few increments over a series of several frames or the camera can move around an object.

The first method was how the first cartoons were created. A cartoonist would draw say a car with a blue sky and sun on a sheet of paper that we will call a frame. This would become the 1st frame of the cartoon. The next frame would again show the blue sky and sun. This next frame, however, would show the car drawn a bit offset from the first. After a series of say hundreds of frames if one looked at them consecutively and fast the illusions of a car moving could be seen. As one can see this method took forever and was time consuming having to create hundreds of thousands of frames for a full-motion cartoon. Thanks to advancements in technology and cartoonist tricks this methods was soon streamlined.

I am not sure where or when the 2nd method was started, but I would think it started in the movie industry with outer space films. The concept is simple. Movement is relative to the viewer’s vision. By moving a camera that starts off at a distance closer to an object the final result on film is the viewer getting closer to the object. If one adds a background to the object and makes the background move as well the illusion that the main object is moving closer to one is created. Think of fast moving star wars space ships. The small model ships were NOT really moving. The camera was and the illusion of speedy spacecrafts was achieved.

For this tutorial I will demonstrate the first method of rendering. The second method is most useful when trying to create the illusion of speed in space. This will be covered in another tutorial (Lego Animation 102: Movement in Outer Space)

As stated in Step 2, we will have to code the animation in this Step. This can be a daunting task for the non-coders but the steps below have been created with these readers in mind. These steps assume that the reader has already installed POV-Ray onto their computer systems. Read the POV-Ray homepage [6] for installation instructions.

1. Create a folder called animation and move the .pov file create in Step 2 into it. Open the .pov file created at the end of Step 2. Ours will be referred to as 4565_Engine.pov in this tutorial. Upon first inspection this file may seem huge and a challenge to read. However, 98% of the information in this file will NOT be used.

   

2. At the top of the file you will see a series of #declare lines. The only one important is the one highlighted in red.

   	
   #declare QUAL = 2; // Quality level…
   

   Make sure that the quality level is equal to 2 for FINAL rendering. It is recommended that you use level 1 when working on figuring out where to place the camera and when doing initial key animation frames if you have an older machine. Note that it is NOT RECOMMENED that you use level 3 unless one owns a high-end workstation PC or a dual-processor power Apple as rendering times per frame will take 5+ minutes. Level 3 requires A LOT of processing power and memory. The quality difference between 3 and 2 is not noticeable for animations. If you are doing still images, use quality 3 for the best results. I have done animation rendering on a dual P-3 1.4 GHz & 512 MB Ram machine and the time was still very slow.

   

3. Now scroll to the bottom of the file. Look for the highlighted information in red in the image above. This is where the major parts of the animation hand coding will take place.

   Object { _4564_Engine_dot_dat … } is the command line that tells POV-Ray that all the lines above it create the 3D train engine. To this line we will be adding a command that will allow us to move the engine train object across the screen.

   Background { color rgb <0,0,0>} tells POV-Ray to create a background with the color in parenthesis. One can change the color of the background by changing the values of the numbers. Rgb stands for red, green, and blue and acceptable values range from 0 to 1 for each color. Values above 1.0 can be used to create a bright neon color effect. The name of the game here is to experiment with the values. 0 means no color while 1 means full color saturation for the color in question.

   Camera {…} is the command that lets POV-Ray know where the camera should be placed and in which direction it should be looking. The only thing to remember when working with the camera is that in ldraw the sky is on the –y axis. Thus when rendering in POV-Ray remember that the sky is in the –y axis.

   Light_source {…} is the command that lets POV-Ray know where to place lights in the environment. You need lights in order for the camera to see. Think of those big lights used in the photo studio. By placing the lights in various locations around the object you can get different effects.

   

4. The biggest challenges we have to creating the animation is to 1) find out where we want to place our camera 2) where should the camera be looking at 3) how much to move our train in each frame and 4) how many frames to create. By default our object is centered at <0,0,0>. According to our storyboard we want to see the train engine move from right to left across the screen. Thus looking at the image below we should place our camera off centered from the middle of the frame looking at the red dot.

   To place the camera in the desire location we need to modify the camera line. First delete everything that is between the { } of the camera line. Next add the following lines

   

   Note that I have changed the background color from black <0,0,0> to gray <.5,.5,.5> To render the image 1) ensure that the proper .ini file is being used. Click on the ini button to get the POV-Ray from Windows render setting window. Ensure that the name of the ini file is “QUICKRES.INI” if it is not click on the default button and then click on the “Set but don’t Render” button. The QUICKRES.ini file is the basic file used by POV-Ray for rendering. Later we will create our own .ini file for our specific animation. For now, however, we just need to quickly render some still images. Next ensure that the image size is set to 160x120 No AA. Under the New button is a small drop down window listing a variety of image file sizes. For our purpose the smallest file size is best since we are trying to get our coordinate system down right. Last click on the Run button.

   So how did I know what numbers to use? Trial and Error! We know that the train engine is at <0,0,0> (x-axis, y-axis, z-axis). Thus we need to move the camera on the x-axis. I first tried <100,0,0> and the results were not good. The camera was too close to the engine. So I moved the camera some more to <2000,0,0>. At that position the camera was too far. Experiment with different numbers to get the desired location you want. I left the look_at location at <0,0,0> since this will have the camera looking at the center of the train engine. You can change this off course but for our animation we will leave it alone. The angle command tells POV-Ray at what angle to place the camera. Again experimentation is the best method here.

5. Okay so now that we have our camera in place we need to move the engine to the right so that it starts off the screen. To do this we will add a line of code to the object line.

   

   We use the command line translate <0,0,-750> to move the engine to the left of the screen. The translate command is used to move an object. Again, how did I know what number to use? Trail and Error, at first I used <-500,0,0> but this made the engine go further back into the screen. So I changed my movement from the x-axis to the z-axis. I knew it would not be the y-axis as this would move the engine up and down. Thus location <0,0,-750> will be the first frame for the animation. This is storyboard 2! Storyboard 1 will have nothing remember! Now we need to find the location of where the engine will stop to fulfill the requirements of storyboard 3. Again we can render another still image and change the translate code or we can say that translate <0,0,0> will put the engine in the middle of the screen and thus storyboard 3 is complete. To finish up we need to know how far to move the engine to get it off the left side of the screen. Again some more rendering and we see that translate <0,0,750> is the cut of point. So to summarize the key events for the train engine are <0,0,-750> starts off at left side, <0,0,0> engine is at center, <0,0,750> engine is at right side.

6. Okay now we are ready to create our animation but first we need to create an .ini file for the 4565_Engine.pov file. The .ini file will let POV-Ray know how many images to render and how much it should move our engine in each image. It will also let POV-Ray know what file to render, the size of each image and many other things. Open up the 4565_Engine.ini that I have provided in POV-Ray. To do this go to the ini button and use the browse to look for the file. Then click on the edit button. You will see that the first line is a comment line. It uses the “;” to denote that this line is just for the reader to obtain information on the file. POV-Ray will ignore this type of line. The next line informs POV-Ray what file it will be rendering. In our case 4565_Engine.pov.

   Now for a bit of what comes in Step 4, producing the video. At the basic level a video can have 25 or 30 (technically speaking 29.97) frames per second. These are the US standards; European standards are a bit different and will NOT be discussed here. In the movie theaters they use 30 frames per second. What this means is that each second the film camera is sending 30 frames to the screen. The human eye sees this as continues movement. One can go as low as 15 frames per second but at that rate the human eye will start to see that the movie is really a series of images. So we want to create an animation in which the train takes 3 seconds to come in from the right and stop at the middle. Then wait for 5 seconds at the middle and finally take 3 more seconds to leave the screen. Thus total running time is 3 + 5 + 3 = 11 seconds. At 30 frames per second we need 30 * 11 = 330 images! Looking at our animation time we can see that we have 3 smaller animations: a 3 second engine coming in from right side of screen,a 5 second engine idle at center and a 3 second engine leaving the screen. Thus we will have 3 rendering runs to do. This means that we will have at least 3 ini files. One for each rendering run.

7. .ini File 1: Engine coming in
   This rendering will require 90 frames. (3 seconds * 30 frames per second). So looking at our 4656_Engine.ini file we see that the initial frame will be 1 and that last one will be 90. This will tell POV-Ray to create 90 images, beginning with image 1 through 90. Next we need to set the clock variable. The clock variable will be used to move the train engine. Remember how we found the end points using the translate command. Well the initial_clock value will be –750 and the final will be 0. This is where the beauty of POV-Ray lies in. POV-Ray will calculate what the clock value should be for all the intermediate frames 2 – 29 using the end point of the clock value –750 though 0. But how will the 4565_Engine.pov know how to use the clock value? Simply insert it in the object line. Instead of using translate <0,0,-750> we add translate <0,0,clock>. Next up is the size of each image. We were using 120x160 for testing purposes. However, the final animation will be of the 320x240 size. This size will make a decent size video file with good quality but not create a very huge file. Look at the QUICKRES.ini file for different file sizes. Next specify what type of file format you wish to output. In our case we will use the N for PNG format since Ulead MediaStudio Pro 6.0 can handle this type of format. One last note before we begin to render. There are two comment lines in the 4565_Engine.ini file that I will talk about briefly. Subset_Start_Frame = 1 and SubSet_End_Frame = 30. If for some reason you need to stop the animation rendering before all 30 images are complete. You can use these commands to complete it at a later date. Say you stop the animation when the 15th file is completed. If you then come back and set the Initial_Frame = 16 and the Final_Frame = 30 then the clock calculations will be based on 14 frames and NOT the original 30 frames. Thus you must use Subset_Start_Frame = 16 and Subset_End_Frame = 30 for the clock variable to be based off the original 30 frames.

8. Okay we are now ready to render. First set the correct .ini file. Use the ini file button and browse for the 4565_Engine.ini file and click on the “Set but don’t render” button. Now click on the 4565_Engine.pov tab and click on the run file. The animation should begin and now it’s a question of waiting for all 30 images to be complete. You can pause the rendering by clicking on the pause button in POV-Ray if you need to free up computer resources. You can stop the rendering anytime by clicking on the stop button located where the run button was at when you began the rendering. Note that in this example our rendering times are small because we are using a simple file. If you plan on creating more complex animations the time it takes will increase. There are several ways to help decrease this time. First, close any other programs you may have running. Secondly, in the system tray (bottom right hand side of you PC) close off any automated applications, (Disable anti-viruses software, pop-up killer, etc.) and third before hitting the render button go to the render file menu in POV-Ray. When the drop-down menu appears go to GUI Priority and set to “lowest”. Next go to Render Priority and set to “Highest”. Then hit the render button. If you use these setting you mouse will have some serious lag time to it. Be patience. It is recommended that for long rendering time you use these setting and let the computer run over nighttime. Your PC will be happy with you if you just leave it alone and let it due its job.

9. Once the animation is done go open up the folder where you had the 4565_Engine.pov and you will notice that it now was 30 new files called 4565_E01.png through 4565_E30.png. These are our animation files that correspond to storyboard 2! Create a sub-folder in the animation folder and call it StoryBoard_2 and move all the .png files into that folder.

10. Now we will create the images for storyboard 3. This will be an easy one since the 150 images that we need are all the same. The train engine is NOT moving so there is no need to create 150 images just 1. In Step 4, we will tell Ulead MediaStudio Pro 6.0 that this image will have a 5 second time to it as oppose to the rest that will have 1/30th of a second (30 frames or images per second). There is no need to render these images as the last image of storyboard_2 is the image in question. Create a new sub-folder in the animation folder and call it Storyboard_3. Look in the storyboard_2 folder for the 4565_E30.png file and copy it to the storyboard_3 folder. Rename the file to 4565_SB_3.png

11. Now we need to complete the images for storyboard 4. This one is similar to storyboard 2 in that it requires 90 frames. We need to edit the 4565_Engine.ini file for this rendering. Everything will stay the same with the exception of the clock variable. Instead of starting at –750 and ending at 0. We need to start at 0 and end at 750. Thus Initial_Clock = 0 and Final_Clock = 750. Okay now rendering the 4565_Engine.pov file.

12. When done rendering create a new sub-folder called storyboard_4 and move the newly created images 4565_E01.png through 4565_E30.png to the folder. Now it’s time for some film production.

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