Mike's Troubleshooting Page

Over the past two years I have decided to post some real stumpers on this page. Some of the answers came from actual effects artists (Scott Squires for instance) and some I just solved myself or with the help of highend3d.com. This page covers the following applications:

• Maya
• Commotion Pro
• RealViz MatchMover
• Entropy & MayaMan (discontinued)
• General Render Tips

Maya 4 

 

When Using the G.I. Joe Fake (Global Illumination) MEL Script I Can't Get Specularity to Appear On My Models? What Am I Doing Wrong?

The G.I. Joe Sphere/lighting rig seems to suck out all specularity from my model (uses color, bump, and specular maps). I am using Blinn shader material. The bump map is not pronounced as well. When I use just three directional lights (using Depth Map shadows) I receive specularity and the bump maps appear as well. What am I doing wrong? Does it have to do with baking shadows in or something? The image on the left shows the G.I. Joe render. The image on the right shows the render with three directional lights (using Depth Map shadows).

Maya 4/Mental Ray Issues!

I am using Maya 4.02 (win2k) and mental ray for Maya and want to render an oil can that has several textures to make it look photo real. I have GI turned off and am only using the Final Gather feature, but the renders always show up "a nice overcast-lit Gray! Why? Why don't  the texture maps appear in the render? This is true even  if I activate GI as well?   A|W really needs some tutorials and troubleshooting docs for this product. On the left is a standard Maya 4 render using a sphere of directional lights to simulate global illumination (the 50 directional lights do not emit the specular component of light). On the right is the Final Gather (no GI) with a 250 value (1000 didn't do anything). Any suggestions as to what I am doing wrong?

Answer: TBA

   

Question: Why Can't I Get a Sky Reflection On My Plane's Cockpit (Glass)?

I am using a standard blinn (glass) shader on my cockpit. I have used a spherical array of directional lights as well as single directional lights emitting (both specular and diffuse). I mapped an Environment Cube to the Reflectivity channel. This cube uses 6 (planar) projections around the plane. 

The above image is a test render (raytraced). A non-raytraced also did not produce any sky reflections.

Answer: Attach a Blinn Glass shader to the cockpit. Make sure the glass shader you use does not have anything mapped to the Reflective Color. Many glass shaders do have something (some sort of ramp). Create an Environment Ball and utilize a panoramic image.  

Question:  Rendering Shadows onto the UseBackground Plane - How to 
Turn Off Visibility of (entire) Model

I am a bit confused on how to turn off "primary visibility" on my aircraft models in my scene. In the outliner the model is one entry representing all of the grouped geometry. But when I highlight it and display the Attribute. Editor to flip off the "Primary Visibility" a check box is not available? The simple sphere in the scene does render  properly and can be turned off in the fashion described. It also renders a shadow in the alpha channel from the Use Background plane. The light is a directional light with Depth Map resolution set to 512. 

So what does one do when trying to disable "Primary visibility" of a complex model? I am using Maya 4.01 on Win2K. Click on image below to see actual screen shot.

Answer: You can disable the primary visibility for numerous objects (of a group) at once using the Attribute Spreadsheet.

The Attribute Spreadsheet editor  is used for changing multiple values on multiple objects all at the same time.  Select your plane group then go to Window->general editors: attribute spreadsheet.

Now you must go to the render sheet and scroll left till you see primary visibility.  Click and hold in the first "on" field and swipe all the way to the bottom of the fields.  Then type "off" or the number 0 and hit enter.  All of your objects' primary visibility are now off.  This is an irreplaceable tool.

Question: Duplicating a Model Reverses Texture Map Image!

My texture map images are reversed once I  make a duplicate of a texture mapped model. How can I prevent this texture map reversing when I want to make multiple copies of the same model in a scene. A sample render is shown below. Notice the number 12 on the side of the Messerschmitt aircraft. The closest aircraft has the side texture map reversed? Click on the image to enlarge. 

 

Answer: Always reset the Duplicate menu. I had used a -1 translation in the Y-axis in a previous duplicate operation earlier in the day and forgot to reset it.

Question: My Polygon Geometry Disappears after applying a texture to the color channel of a blinn material? 

As you can see after applying the image file in *.iff format  (which has the side image of the plane as a texture map) the geometry actually disappears in h/w texture mode. Pressing the 4 key reveals the geometry is actually still there? Anyone have a clue as to what causes this?

Here is my workflow:

I successfully mapped the wings and now  I want to  texture map the side of the plane.

1.  Create a new blinn shader.
2. Assign the new material to the plane.
3. Select an image file (*.iff) to use as a texture map. Click on folder icon to assign a file and the geometry goes invisible in hardware texture mode (press 6 key)?!!?

  In H/W mode it looks like half of the model was deleted.

NOTE: If you want a detailed ( eight-page description)  step-by-step instructions or the workflow to try yourself, read the pdf file. Here is a screen shot of my model with the invisible geometry. Click to enlarge.

Ironically, the  Maya 4 Release Notes do mention part of the problem, but not the true solution. Although the problem really isn't noticeable until you attach an image file to the material. The text really should be more focused. 

From the Maya 4 Release Notes:

Limitation: Polygonal objects or portions of polygonal objects with no UV textures coordinates appear "stippled*" when viewed in hardware texture shading mode (hotkey 6).
(*looks kind of invisible or x-ray view)


Alias|Wavefront Workaround: Create new UV coordinates by selecting the faces of the object and using any of the following tools in the Edit Polygons>Texture View menu:
- Planar Mapping
- Cylindrical Mapping
- Spherical Mapping
- Create UVs based on Camera
- Normalize UVs
- Unitize UVs
- and Best Plane Texturing. 

If you do not want to create new UVs you can view the object properly by viewing it in the shaded mode.

Answer: ...and here is the "True" solution. I discovered this after over a month of brief discussions on highend3d.com and  still no one solved this problem! Follow the steps below:

1.  Select your material.
2.  Select  Window>Rendering Editors>Hypershade....
3. Click the Graph Material on Selected Objects icon.
4. Double-click on the material shader.
   The Attribute editor appears.
5. Select the "Hardware Texturing" section and ensure that the Textured channel is set to Color.  
6. Change the Texture quality value from the default value to the highest value. After a short calculation ( the hour-glass icon appears) the texture is properly displayed on the geometry.  

Question: Why Are My Rendered Planets Squashed?

In Maya 3.0a I am rendering my scene and getting squashed planets. The spheres are not rendering round! Why? I have toggled between Digital Video and CCIR601 because I want to output to digital video tape. Is this a render globals adjustment? Does it have to do with square pixels? A sample render is shown below:

Click on image to enlarge the file.

Answer: Change the aspect ratio from .9 to 1.0 in the Global Renders dialog box.

Question: Why Do My  Texture References Keep Appearing in the LightFog?

I have a scene with a lot of texture mapped polygon asteroids. I have applied "Create texture 
reference objects" to these asteroids to keep the maps from swimming. The asteroids do rotate and move slowly from scene left to right. I have selected all reference objects from the Outliner and hidden them. My problem, is that they show up as dark shadows in my final render. I have also placed some of these texture reference objects on layers and hidden them as well. And yet they still show up!!!!

What am I doing wrong? I have a large nurbs surface with the blue galaxy mapped to it and use a spotlight as the main light source. I also have a directional light near the camera to cast the shadows seen on the asteroids. The spotlight also uses a lightFog1 material under special light effects section. I also use a depth map of 1024. Any suggestions as to how I can get rid of the image cast by the texture ref objects? They are most visible in the upper right quadrant of the image. The images are shown below.

 

     

Answer: I placed the spotlight on its own layer and hid it when I rendered. The shadows from the  texture reference objects no longer appear in the final render. 

  A.Tool.Fan@aol.com comments: Texture references are created and templated and should stay that way (thus they will not render and they wont be interacted with by the user and broken in any way).  However, if they are not templated they will appear in  renders.  You should either hide them altogether or turn off primary visibility as well as  turn off cast shadows.  If you hide an object in maya it is not visible to  the renderer therefore it is not calculated in reflections, shadows or any other means that the renderer would normally calculate (in fact, hidden objects are not even tessellated).

Commotion Pro

Question: Adding Time Stretch to a Clip causes the Image Edge to "Chatter". How Can I Stop This?

Please take a look at this sample  render (720x480, 500KB AVI file). It uses the DivX codec. Or you can download the QuickTime file (320x240, 500 KB). After adding a 130% Time Stretch to the Battleship clip and its shadow clip, the resulting render produces a noticeable chatter around both the Battleship and its shadow. The Time Stretch worked well slowing down the movement of the battleship (and shadow) to give the illusion that the large ship is closer to the "far away" cliffs. In addition, I applied both the Composite Color Matcher  and Light Wrap features to all ships in this scene. 

 

 

Question: How can I add reflections (Egyptian columns) in the window of the building ?

Answer: Scott Squires (Senior Visual Effects Supervisor, ILM) replies via wwug.com.... 
As Mr. Boy mentioned you can fake it by scaling your same element. A more correct method is to build a reflection surface in your 3D program and render this so the perspective and image being reflected is correct. Would you actually see the reflections at this angle? Does it reflect the ground the columns are on?

Question: How do I composite my CG element behind an object in my background plate? 

Answer: Scott Squires (creator of Commotion Pro and Senior Visual Effects supervisor at ILM)  replies:  

Bottom layer in the timeline should be your background (explosion). Next layer should be your CG Plane. On top of that now add the BG (background)  image again. Also, make sure all of your clips start at the same frame number.

1. In the Timeline, double click the top layer (BG image of explosion).
   A window appears containing the background explosion sequence. 
2. Now use the roto tool to outline the speaker or object that you want the plane to go behind.

In your Composite window,  the proper areas appear matted out (or more appropriately, rotoscoped out) .  In this case we do not  rotoscope the bottom layer since it would matte the BG area against a constant background color (black typically).

I assume you render your CG plane with it's own matte so it appears correctly. Just think of the top layer as just the speaker from the background plate so the layers are as you would expect them to be as viewed from the camera. speaker > plane > background.

It's possible to do things like:

• Perform  the rotoscoping on the BG plate and save as a file 
• Turn it off for the BG plate and double click the plane
• Next, load in the rotospline file and set rotoscope  mode to subtract 

However, this  and a few other approaches do not provide you with the flexibility you want.

Question: Why am I losing my fog in the composite? How can I prevent this?

I have rendered some asteroids  in Maya 4 with an environment fog effect. This shows up in the alpha channel but when I bring it into Commotion Pro in the "Normal" composite mode I lose much of the fog effect. Can I compensate for this somehow? Or should I rerender in Maya and save out to Z-depth information. Will Commotion Pro use this channel? Any suggestions are welcome. You can see the example screen shot below.

Answer: Scott Squires replies via wwug.com: On your site you mention issues with fog alpha. Use the Filter > Levels selection and then adjust the alpha curve/contrast to get the effect you desire. You could also use the Color Curve filter set to alpha as well.

Question: Whenever I playback frame 178 the composite window appears black. 

In fact when using the player it also stops at frame 178.  The comp is set to be 200 frames long. What was I doing before this happened? I was working in the Curve Editor so the camera would start panning from the bottom of the earth image and stop just before the surface of the planet disappears below the horizon. The moon is in the upper right hand quadrant. Shortly after working with the curve editor I saved my changes and received an error:

Unknown Error (27728) Error message not found

My system is a Windows 2000 (service pack 1) with 512 MB RAM using an Oxygen VX1 graphics card w/32 MB texture RAM (latest Win2K drivers). 

Should I send this to support@pinnaclesystems.com? A screen shot of my desktop is below. Click to enlarge the 92 KB desktop image. 

Answer: It seems I may have accidentally deleted a frame or two from the sequence. This would cause Commotion  to compensate and display a black image in place of the missing element. 

Question: How can I use a still image in the timeline

I have a still image I want to use as the background so I placed it onto the timeline. For some reason I can grab the image manipulator but I can't expand it so that the image is visible throughout the entire timeline like the other elements.

Click on the image below to see my Commotion 3.1 desktop with composite elements. Notice the timeline. 
Why can't I expand the visibility of this image?

Answer: In this case the filename was using a number it and this confused Commotion into thinking that there were several files (as in a sequence) in the directory. I removed the number from the filename and it works fine now. 

RealViz Match Mover 

Question: How do you get rid of lens distortion?

Answer: If by "aspherical" you mean an anamorphic lens, then once you have taken out the anamorphicness with a .5 scale in the y (or, better, a 2x scale in the x), you then have the rest of the lens distortion to worry about.

This might be very hard to do - anamorphic lenses produce some really whacky distortions, and the distortion varies according to the focus - through a pull focus you will see varying distortions. Without either a reference grid shot especially for you with the lens at the focus setting of your shot, or else some of the kind of proprietary software that facilities keep very much to themselves, you might be stuffed. Sorry

Paddy from the vfxpro.com discussion board.

Question: Matching CGI character to background problem 

I have rendered out the sequence shown below but the CGI element is not matched to the  movement of the background? After you align the RealViz camera so that the view encompasses the action of the character do you have to parent the character to a  locator or something? Anyone with  matchmoving experience please take a look at the AVI and make a suggestion. 

Click to see AVI movie (307 KB using DivX codec for Windows).  

Answer: Let's just say that that automatic tracking feature has done a great job in release 2.2. I believe that the canned CG dancer was not zeroed out to world space and thus makes it difficult to use in an actual scene. 

Question:  How can I get the camera to see the CG object at frame 1?

How do I ensure that the imported mocap "animated" CG character is in line with the RealViz camera/image plane throughout the entire animation? 

 I have successfully tracked my background footage using RealViz MatchMover 2 but have problems aligning the imported RealViz  camera with the imported CG character. At frame 1 the camera is not looking anywhere near the imported CG object. I could move the CG object in front of the camera, but when I scrub to frame 1 it shoots back to its original coordinates in world space - nowhere near each other. The dancer is not static and moves around a bit and never appears, even by chance, in front of the RealViz camera at any  frame.  Does this always happen in both export "camera" and "scene" cases? This sounds like a general Match moving question. Or can I   have more freedom in moving the RealViz camera in the Camera export  selection as opposed to the scene export selection? Any comments welcome. The screen shot below shows the mocap dancer in the center of the RealViz camera, but as soon as I go to frame 1 it is no longer in sight of the RealViz camera? What am I doing wrong?

Answer: When you are ready to export your file to your 3D application (Maya 3 in my case) make sure you  choose "Scene" instead of Camera especially if your CG objects are animated. The Camera setting is default. The reference guide actually tipped me off to this but it was mentioned in only two vague sentences.  Maybe put it in a bold NOTE: or mention that when "importing animated" CG objects/characters use the "Scene" export option as this lets you to position the camera to focus on the animated character/object. 

The scene export option lets you select (in Maya's Outliner) and translate the RealViz camera, (track points) locators and image plane and move them so that the animated character is in the camera's viewfinder throughout its entire animation cycle. 

 

Entropy  & MayaMan 

Question: Grainy motion blur in global illumination scene (Entropy R3 & MayaMan 1.03)

I would like any suggestions as to how to improve my GI render that makes use of Entropy/MayaMan's motion blur. In the scene is a half dome with a very light blue color shader. One area light is pointing upward inside the dome. I have a scene with a P51 Mustang and rotate the propeller via a simple expression based on time. As you can see via the attached *.tif file, it is not coming out as nice as I hoped. I believe this to be operator error. I am not a "professional", so I spend hours tweaking settings in the render settings and see if the image improves. I read the Motion Blur description in the documentation but would really love to see "presets" either in the MayaMan GUI or have values for different scenarios listed in the manual.

I did notice that Lightwave has a unique plug-in (LW_VectorBlur) that solves the problem (in-part) when using propellers and motion blur with great results. The URL is below.

http://www.lightwave3d.com/tutorials/rendering/vector_motion_blur/vector_motion_blur_2.html

Answer:  First of all I would suggest testing motion blur and GI independently of each other before testing them together because of how long it takes to render GI especially with the amount of sampling needed for smooth motion blur.  Also note that grainy motion blur is usually a case of low anti-aliasing, however this effect can be more pronounced if added the grainy rendering of a low sampled area light on top of low sampled anti-aliased motion blur.

Motion blur in Entropy is determined in anti-aliasing.  It is not a post process as it is in the vector plugin used in Lightwave.  Also Entropy does not support multi-segmented motion blur yet (motion blur that is sampled multiple times over the advancing of the shutter open-close in order to get arching motion blurs), so your motion blurs will be linear.  Something that most people never notice when the images are in motion.  Plus multi-segment motion blur takes longer to render because it involves additional calculation and  sampling.  MayaMan has two settings for Entropy: spacial sampling and temporal sampling.  Temporal sampling is only for motion blur.  Spacial sampling is for all anti-aliasing (super sampling).  Usually values of two for spacial sampling is fine if no motion blur or depth of field is used.  Temporal sampling  multiplies the spacial sampling value only on motion blurred objects. Moreover, the motion blurred objects receive more sampling than is necessary for  non-motion blurred objects.  This process reduces the render times.  However my experience  is that a Max Temporal value of  eight is not enough for clean motion blur.  So I have to increase spacial sampling to four or six and the motion blurred image appears smoother.

So now that you have motion blur looking smooth, test it again with an area light.  It should look better, however if you have a low sampled area light, the motion blur may appear grainy.  Next, try increasing the area light samples to 64 or 128.  However, this   increases your render times.  It may be better to come up with a lighting scheme that mimics area lighting, but does not use area lights.  Also, if you render your area lights "as primitive" through a MayaMan objects node you can cut down render times (when using Maya's area lights) and improve the image quality.

Finally test your GI settings over night because it will take a long time to render GI with the amount of sampling for the motion blur and the area lights. (contributed by A.Tool.Fan@aol.com).

General Render Tips

NOTE: This information has been harvested from the Maya section of Highend3d.com site. I have edited some of this material  when I have found some free time. 

Question: I am editing a scene with 50-60 texture map files and I occasionally need to find out what the resolution of a particular image is. Is there an easy way to find out what the ACTUAL size is (X*Y size in pixels and/or bit depth) of an image file using the hypergraph (or multilister). 

Answer: getAttr file1.outSize; this will give you the pixel dimensions of 'file1'.

Question: Contact shadow pass in Maya? 

Answer: The easiest method is to use a negative light and parent it to the feet and give it a intensity curve for decay. You now   can control the exact distance of the shadow or negative light....and make sure it only illuminates the ground as to not suck light off the feet too.... I imagine you could also texture map the color as to the shape of your feet making a perfect soft shape in the negative light.... mrPooH.( www.TheLightOmelette.com)

Question:  I have textures that keep swimming while the object moves!

Answer: Texture references  only work on file textures with mipmap filtering, any other setting and the texture slides as if there is no reference. Other than that there is no reason why texture references will not work. Are you trying to stick 3D textures or projections? You do not have to create the reference object before deformations so there's no need to rebind.  Make sure the textures are in the correct place when you create the ref object.  

Question: Contact Shadow success! - cool trick... Poster: lcymet : 07/11/01 06:34 AM Thanks to all the kind folk who posted many replies to my previous request for contact shadow solutions. We happened upon a solution that works quite well and we just wanted to share it... 

Answer: Start with a  plane using the useBackground material and a direct light pointing straight down at the plane (with raytraced shadows activated). Next, create a material with a ramp (as a projection) in the transparency map. Adjust the placement node and the ramp itself so that the ramp starts with a 0 transparency value at the ground plane and quickly gradates to 100% transparency right above the feet of your character. The idea being that you make only the objects that are near the ground visible. Apply this material to your character. Do not use a texture reference! You want the character to swim through the transparency map so that any part of the character that comes into contact with the ground is made visible and the geometry above gradates smoothly to transparency. Turn on raytracing in your render globals (so that the shadows obey the transparency map) and your done. It may be a bit slower, but the effect is great. Since you will probably blur the shadows anyways, half-size renders should work as well. Good luck! (Laurence Cymet Calibre Digital Pictures.)

Question: Re: how to use maya's Z channel Poster: beaker : 07/15/01 06:15 PM 

Answer: Use *.sgi or *.rla files.  Both of these file types support built in Z- channels. I know for a fact that After Effects reads *.sgi files, but I am not sure about *.rla files. The only way to use Maya *.iff files with After Effects is to use the Photoshop iff plugin, but it is buggy and I am pretty sure that it reads the Z- file as just a second alpha since Photoshop does not handle Z- files. Deke Kincaid deke@mail108.pair.com.

 

 

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