Arnold For Maya – Lights 3...

Area Light   Maya Area Light Leave as the default Intensity and Exposure value. Turn off Normalize. Scale the area light. Adjust the light effects by scaling the size. Area Light from Arnold parameter    Arnold Area Light As a default setting it renders very dim because of the quadratic fall off. Turn off Normalize. This works exactly like maya area light. But it has an additional option. That is light shape. It can be changed to cylinder, disk or quad. Mesh Light The last Arnold area light is mesh light. We are able to use any mesh within our scene as a source. Create a geometry and go to the Arnold menu and select mesh light. ( your geometry must be selected when you select the mesh light.) It will create an area light with the same shape of your geometry. You must keep your original geometry in order to use your area light. Turn off Normalize and visuality off as you wish.   Read the rest of articles Arnold for Maya – Part 1 Arnold for Maya – Part 2 Arnold for Maya – Part...

Arnold for Maya – Lights 2...

Light Filters   LightDecay changes how the light starts. The start point doesn’t have to be brightest. It can start very dark and get brighter when it gets further away. Near Attenuation Far Attenuation   Barndoor   Gobo   Light Blocker   To be continued in part 3       Read the rest of articles Arnold for Maya – Part 1 Arnold for Maya – Part 2 Arnold for Maya – Part...

Arnold for Maya – Lights 1...

This note explains how to use both the default Maya lights and Arnold specific lights in Arnold renders.   I am going to start with a default maya point light.   In the attribute editor of the point light, see  the decay type under Arnold menu: In comparison Quadratic came out very dark compared to Constant. The reason for this is the decay rate. To make it physically accurate we need to increase its intensity , exposure, radios and sample etc.   Below is an example of Exposure, radios. I increased the sample value to reduce the noise from increasing radios.   Shadow density: How density shadow should be. The default 1 as it is physically accurate. Volumetric Fog:  Enable “aiVolumescattering” in the render setting.   Default Maya light type   Directional light Exposure: we can make it brighter or darker. Angle: makes it more diffuse in the edges but the contacts are still sharp. Samples: Increasing this will reduce a lot of noise.   Spot light Using the default spot light the rendering came out really dark because of fall off. So increase the intensity and exposure as well. Adjust cone angle, penumbra Angle and drop off ( Controls the intensity base on the center to the outer edge of the light). Intensity, Exposure, Penumbra, Drop off Aspect Ratio The aspect ratio will give the light more of an anamorphic shape. Lens Radius Lens Radius is how large the light source should be. ( I have enabled the volume scattering in my shot for the demo.) To be continued in part 2   Read the rest of articles Arnold for Maya – Part 1 Arnold for Maya – Part 2 Arnold for Maya – Part...

Arnold for Maya – Image Based Lighting...

The following article explains how to use image based lighting using Arnold within Maya.   Image Based Lighting simulates light from a hemisphere or dome above the scene representing the sky. It can also be used with high dynamic range (HDR) images to perform image-based environment lighting. This is the node which is typically used for lighting exterior scenes.   Go to Arnold top and click “Lights” and then create a “SkydomeLight”. If you change the scale or position of the skydomLight it would not do anything. It would only make a difference  if we were to rotate with HDR image applied onto it. Make sure there are no lights in your Maya scene. When you render as it is you get a Gi_based render. Most of the Skydomelight property controls is within the SkydomelightShape in the attributer editor. For example color, intensity, use color temperature etc. HDR images have a greater capacity to describe light accurately (by way of floating point numbers) because they store the amount of light (rather than just color) represented in a pixel. This prevents ‘blown out’ or extremely dark areas in an image that your eyes compensate for in the natural world. How add an HDR image into the scene.     Sample: Controls the quality of the noise in the soft shadows and direct specular highlight. The higher the number of samples, the lower the noise, and the longer it takes to render. The exact number of shadow rays sent to the light is the square of this value multiplied by the AA samples.   In my case, this AA increase allows me to decrease the other sampling rates (GI/glossy/light) to compensate. To sum up, I get almost the same render time with AA=1 and GI=9 than with AA=9...

Understanding the basics of CG Lighting...

Through all my years in the movie making industry I have studied the intricacies of CG Lighting techniques and have come up with the following article to give those just getting started some baseline knowledge on the concepts involved. Hope you enjoy! Overview Source of Lights Basic Lights Basic Lighting Setup Shadows Imaged Based Lighting Lighting Effect Source of Lights Including both natural and artificial sources This is a list of sources of light. The sun, moon, fire  and artificial source such as light bulbs etc.    Sunlight “Painting” and Sunlight “CGI”   In the past, artists observed and mimicked whatever there is in the natural world that they desired to paint. We can find several lighting conditions in the natural world or environments such as the most common and natural phenomena – sunlight. We have here on this second example, a computer generated image using the same sun-lit technique, forcing computer artists to do the same as painters to mimic what is in the environment world.   Candle Light   In an example of artificial light, such as light candles or light bulbs a similar challenge forces all kinds of artists including CG artists to follow the same rules of physical lighting. Most of the time using artificial lights helps achieve very dramatic scenery.   Basic lights   We have different ways of achieving these lighting effects. The most common lighting techniques used in any 3d program are spot lights, point lights and directional lights.  With these, we can achieve any result we desire in creating CGI images.   Key light A main light. It simulates the sun or moon. It also provide a main shadow on the objects.   Fill light No direct light. It could be sky or ambient.   Rim lights...

General Lighting Adjustment in Nuke...

General Lighting Adjustment   Continuing this note from “Foreground Compositing in Nuke” which I posted 8th of Nov.   We have the neutralizer color correction “Grade2” which is right under Transform node.  Get the HueCorrect and drag and over the line between Grade2 and Keymix. To do HueCorrect, look to the HueCorrect node then put the mouse over to the area closer to the green screen and to see what color it is fall into. On the edge of step here on the hue graph here the yellow line keeps indicating the value where the mouse is. Click the g_sup on the hue graph. It stops around 1.7 in the hue region. The section we want to pull down where the arrow is. You can’t drag this horizontally and vertically at the same time. Drag the point over the yellow line . Then you can pull it down to the control point and also pull down right to the next one to get rid of more of the green. You can play around with the left control point to get some red back. Now you can toggle off & on  the HueCorrect node. It looks natural and less green. However we pull the green light out it becomes darker. To solve this problem: On the color figure, the angle of the circle is the hue, it is kind of unwrapped. So the result is  the reduction of luminance. One of the solution for this to go up to Luminance ( command+click on the Luminance curve) then reduce the brightness without reducing the green color.. If you look at the set, the wall of background is not definitely white. There are some lights from the fountain or some bounce lighting seated on the wall. So the stair object should be tilted by interacting...

Tracking part 2 in Nuke...

Tracking part 2    Lens distortion Grid in Nuke    I have an over 700 frames of a footage to track. 1. Set up the project settings correctly. Press “s” to bring up the settings. Then change the format to the full resolution of the image. The resolution settings should be there at the bottom of the list. Set your frame range. In this case, the frame range is “0 to 791″. 2. Connect to the Lens distortion which we made earlier. “Toggle Off and On” on the Lens distortion  node. Then you will see the difference between the settings. You should find that it correctly fixes the lens distortion. ( Tip: whenever you change the zoom or your focus, you have to re-shoot the lens distortion grid in theory.)  “Command+x” to disconnect  the lens distortion  node from the footage for now. 3. Get the “CameraTracker” and connect it directly to the source footage. 4. We are going to copy the value of the distortion to the CameraTracker from the LensDistortion. Double click the lens distortion node, you will see the Radial Distortion 1 and the Radial Distortion 2. In the CameraTracker property click “Lens” tap. As a default, you see Lens Distortion is set to “No Lens Distortion“. We are going to choose “Known Lens” ( In this case, we know our lens’s value). For the Lens Type, choose “Spherical“. 5. Go to the LensDistortion property, Radial Distortion 1. Move your mouse to the animation menu box to the right,. Your mouse cursor will change to a mickey mouse hand. Grab it and move to the CameraTracker’s property’s Radial Distortion 1. Repeat the process for Radial Distortion 2. Now you have the match values for the CameraTracker. Once you are done, check on “Undistort Input” on the CameraTrackers...

Tracking part 1 in Nuke...

Tracking part 1 in Nuke   Lens Distortion Grid in Nuke 1. An Image of Lens Distortion Grid: Shooting Lens Grid which should be big enough to cover the entirety of a shot in focus. That gets pretty expensive. In this practice we use a laser tweezer, shoot a blank  wall and cover them horizontally and vertically. Make sure to get the right lens setting when you shoot. (Distortion patten should match) Still image Max Image 2. Isolated Red channel ( because it gives most visibility). Get shuffle node and set it to RED. 3. After shuffle node, attach Lens Distortion node. 4. Lens Distortion node has 3 different way to analyze the distortion and in this case we are going to use Line Analysis. 5. In the Line Analyses tab,  you turn “Drawing Mode“on,  Click to the right of the center of the line and click again further down repeatedly. When you get the last point and made a mistake you can click “Delete Last Point” and re-click on the line. When you get the last point, right click and that closes it out. Go to the different frame and make more lines. ( Tip: Command+Z (undo) doesn’t seem to be working.) 6. When it is done, turn off “Drawing Mode” and click “Analyses lines“. Go to LensDistortion tab and check the “Undistort” check box. This is a very minor lens distortion there but it still closer. 7. If you know you are working on lots of shots which need the same lens distortions, select the lens distortion node then go to “ToolSets” ( Left corner of Nuke’s interface). Name it Click the “ToolSets” icon again now we have a section called adduction/lensing. It will now load up for any shots you...

Face replacement in Nuke...

These are my notes from my nuke class with Damian Allen. Face replacement with Nuke 1. Left pics -> Source face, Right Pics -> Target face 2. Add Tracker node -> Put a tracker node on his chin’s jewel and two other trackers on his eye ends. How to run tracking Get one track on his chin’s jewel – The target is very clear so we can run tracking at once.    For tracking on man’s eye areas – The model is blinking between fr 38 to fr 55. Run tracking frame by frame till he blinks Use clear_fwd or clear_bkwd ( the top right corner ) to avoid the eye area. Hold command + grab the tracker box, move away from the eye area to the eyebrows. click clear_offset  move the track point back to current tracker position ( after he blinks) continue tracking, when he blinks, repeat it the same way. 3. I have made three tracks for the target face.   4. Create a Corner Pin2D Click to From in Corner Pin2D – copy the value from track1 ( Screen Lf eye ) to from4 – Tip:  select the track you want then put the curser to the right side bar, you see the curser changed to hand shape then drag and drop to the CornerPin2d “from4” in this case. copy rest of them.  When pairing up the Tracker with the CornerPin it is wise to ensure that the position of the Tracking points and the CornerPin points correspond with each other (default is anti-clockwise from bottom left).  I only create 3 tracks and we have 4 corners to fill. We need to add some expression on from 1 and from2 from1 x: Tracker1.tracks.3.track_x-50 Y: Tracker1.tracks.3.track_y from2 x: Tracker1.tracks.3.track_x+50 Y: Tracker1.tracks.3.track_y In the CornerPin from tab press copy to. This will copy...

Foreground Compositing in Nuke...

Foreground Compositing in Nuke 1. Background and Foreground Images. Background : an actual scale, Foreground: 1:4 scale 2. Extract the green channel from the foreground. Add Grade node : It is easier to extract the green channel. Use a color picker to get values on the whitepoint and blackpoint on the grade node. Press this icon and you can grab a color from whatever is in your viewer. Following are so helpful keys commends. Command click in the viewer window to sample a pixel point within it. Command + Option will sample the color from the image before the current operation. If you don’t do this it will sample live from the viewer windows ‘’post adjustment’’. Shift combined with any combination of these key strokes will draw a marquee around a sample area. Beware: When you have finished with the color picker press it again to disengage it or it will continue to sample.  3.  Add KeyLight (I called this CoreKlight) node to extract the green channel. Get the screen color value and adjust the tuning. 4. Extract the rest of the foreground besides the stair. Add Grade, Erode (fast) and blur. For the RotoPaint ->I added a blur node / value 3 Then connect this to the Edge KeyLight Then add In node – The matte has been created. 5. Add Key mix to...

Temperature.py in Python...

A module that asks the user the following question: Press C to convert Celcius to Fahrenheit Press F to convert Fahrenheit to Celcius: Note: You have to make sure to accept either lowercase or uppercase C's and F's. Then it will use the mathematical formula for the conversion and print out something like this: X degree Celcius == y degree Fahrenheit and vise versa. My answer is: choice = raw_input(‘Enter Temp in (C)elsius or (F)ahrenheit to Convert to the other: ‘) if choice == ‘c’: x = input (‘Give me the Temp in Celsius: ‘) print “The Temp in F is” , (9.0/5.0) * (x + 32) , “degrees” elif choice == ‘C’: x = input (‘Give me the Temp in Celsius: ‘) print “The Temp in F is” , (9.0/5.0) * (x + 32) , “degrees” elif choice == ‘f’: x = input (‘Give me the Temp in Fahrenheit: ‘) print “The Temp in C is” , (x – 32) * (5.0/9.0) , “degrees” elif choice == “F”: x = input (‘Give me the Temp in Fahrenheit: ‘) print “The Temp in C is” , (x – 32) * (5.0/9.0) , “degrees” else: print “You must give temperature in C or...

How to extract Foreground from Green Screen without having Edge issue in Nuke...

1. These are my notes about how to extract Foreground  from Green Screen without having Edge issue. 2. To key out the  Green Screen using Keylight. The Keylight seems to be more powerful and you can come up with some really good results. Then the image looks like this: 3. Add Background Because of how we multiplied the black background in the process we did earlier it left black edges on her arm. So let’s take of this problem. 4. To make an Edge Matte for Mixing the background to the Edge of the Girl.   Blur Node – size 100 Merge -Xor Grade – Multiply 4 The resulting Image of the final Alpha Channel: 5. Added Background Image to the FG using the mask we just created. Add IN with the FG and another IN for BG The resulting Image 6. Final The Edge of the girl is mixed with the background          ...

How to Create a Matte from GreenScreen in Nuke...

1. This note is how to create a matte from a Green Screen shot. You would do this if there was no alpha channel provided for the foreground   2. Get green channel and red channel from the the GreenScreen 3. Get Merge Node, using Minus to subtract from Green to Red   4. Add Grade Node and lower your whitepoint for the background. In this case it worked with the value 0.055   5. Add Invert and Clamp 6. Final...

Reflection & Highlight Flares in Nuke...

These are my notes from my nuke class with Damian Allen. Basic of Reflection & Highlight Flares 1. Passes – Robot (Chars), FG, BG, Shadow, Matt ( Vignette) 2. Bg Shadow using Grade node. 3. Reflection Flip Transform: Translate Y – put the right position this case I put “17” Scale h -> -1 Center Changing the pivot. Hold down ctrl+alt and now you can move the pivot in the 3d viewer. 4. Add HighLight Flares on Robot’s surface. Using a Keyer: mainly used for luminance-based keying or luma keying. 5. Add Vignette 6. Final Image Damian Allen’s book to read: Buy on...