Mel Lesson 4 Practical Usage 1B

Dynamically copy transform value from one object to the other
continued from Mel Lesson 4 Practical Usage 1A

//====================================

//----------------------copy-------------------
$objTx = getAttr ("pCylinder1.translateX");
$objTy = getAttr ("pCylinder1.translateY");
$objTz = getAttr ("pCylinder1.translateZ");
$objRx = getAttr ("pCylinder1.rotateX");
$objRy = getAttr ("pCylinder1.rotateY");
$objRz = getAttr ("pCylinder1.rotateZ");


Lets modify the above codes to make it take value from any object instead of pCylinder.
---------------------------------------------------------------------------------------------------
ARRAY
string $myObject [] = `ls -sl`;
The above code basically means list selected it stores all the objects name that are selected in maya in the variable called $myObject. Note that this is a variable array unlike a variable it can store more than one value. If you run the above comman after selecting a cone, a cylinder and a cube $myObject will have all the three names stored in it. (Remember the variable stores just the names of the objects and not the object itself.)

You can find the values of the variable $myObject by the using the below command.

print ($myObject[0]);

//result "cone";

print ($myObject[1]);

//result "cylinder";

print ($myObject[2]);

//result "cube";

I guess you have understood what array is.
---------------------------------------------------------------------------------------------------
Now select any object you wish to copy the transform value. Say for example you have selected R_Hnd_Cntrl
Run the below command.
string $myObject [] = `ls -sl`;
//result: R_Hnd_Cntrl

since you selected one object only, the object you selected would be in $myObject[0];

check whether you are right by executing the below.

print $myObject [0];

//result: R_Hnd_Cntrl

Now replace $myObject [0] instead of pCylinder in the command we used in our earlier exercise.
$objTx = getAttr ("pCylinder1.translateX");
 
Since $myObject [0] is a variable and not a string like pCylinder, you have to use it without quotes, which will tell maya to fetch the value of the variable.


$objTx = getAttr ($myObject[0]+".translateX");

You use the "+" to join a string and a variable or a variable and a variable. It is called concatenate-ing

Try the following command to understand better

print ($myObject[0]+".translateX") 

//result: R_Hnd_Cntrl.translateX

To be continued...

Mel Lesson 4 Practical Usage 1A

In this tutorial we will

1. Create a Cylinder and Cone

2. Store the transform values of the Cylinder in a variable (Tip: see lesson 2 Variable).

3. Paste the transform values from the variables on to cone with a click of a button.

1. Create a Cylinder

Create a cylinder and rotate and move it a little so that it has some transformation values.

2. Store the transform values of the Cylinder in a variable

Open your Maya Script Editor

Tip: See MEL lesson 0

Enter the following in the Script Editor:

getAttr ("pCylinder1.translateX")

You will get the below result in the history panel of the script editor

// Result: 1.628443 //

The below explains the what each word means in the above command

We need to store this value in a variable in order to use in future.

All we need to do now is

1. Create a variable (use a name that makes sense)

2. For the value part, tell Maya to fetch the translate X attribute of pCylinder1.

Execute the below command.
$objTx = getAttr ("pCylinder1.translateX")

Maya stores the translate X value of pCylinder1 in the variable $objTx.

If you now now tell Maya to show the value of $objTx, using the below command

print $objTx

it would display the translate X value of pCylinder1:

1.628443

3. Paste the transform values from the variables on to cone

Now create a Cone.
Execute the below code.
setAttr ("pCone1.translateX") $objTx

You will notice that the cone would have moved in translate X, which matched the translate X of pCylinder1.

The below codes will move the Cone to the Cylinder exact position on screen:

//====================================

//----------------------copy-------------------
$objTx = getAttr ("pCylinder1.translateX");
$objTy = getAttr ("pCylinder1.translateY");
$objTz = getAttr ("pCylinder1.translateZ");
$objRx = getAttr ("pCylinder1.rotateX");
$objRy = getAttr ("pCylinder1.rotateY");
$objRz = getAttr ("pCylinder1.rotateZ");
//----------------------paste-------------------

setAttr ("pCone1.translateX") $objTx;
setAttr ("pCone1.translateY") $objTy;
setAttr ("pCone1.translateZ") $objTz;
setAttr ("pCone1.rotateX") $objRx;
setAttr ("pCone1.rotateY") $objRy;
setAttr ("pCone1.rotateZ") $objRz;
//====================================
It is not always pCylinder1 and pCone1 that you want to copy and paste transformation values.
In the next Lesson 4 we will learn how to copy transformation dynamically from any object to any object by a click of a button.

Stereoscopy

Concept
Our two eyes sees objects from a slightly different angle. This around 2 inch difference in point of view helps one eye see the sides of an object better than the other eye. This difference is called parallax. We know how far an object is from us due to this parallax.

How stereoscopy works
The effect of stereoscopy is created by taking 2 images which is shot with a mild horizontal offset (only) and forcefully displaying the left image to the left eye (only) and right image to the right eye (only).


A Quick Experiment
Requirement:
1. A digital still camera
2. A system with photoshop
3. 3D anaglyph glasses (Blue Red glasses)

Procedure:
Take a photo of any thing, preferably that covers object that is far and near.
Slightly shift you camera to your right about 6inches but looking at the same places.
Strictly no up and down and no rotation. Try to be as accurate as possible. Best way is to place your camera on a table take one pic, shift it to the right slightly take another one.
First photo is your left image and second your right image.

Bring these two picture to Photoshop.
Make a psd file with both images as 2 layers.

First check the images whether it will work:
Reduce the opacity of the layer that is on top and see whether the images are matching horizontally. There will be vertical offset though.

If it is looking good reset the opacity back to 100%.


Now the challenge is to force your left eye see the image that is taken from left and the right eye see the image that is taken from right.

There are many methods, for home experiment we can only think of anaglyph glasses (spectacles with red color glass for one eye blue for the other).

What these glasses do?
Basically, the red side of the glass cannot see red channel of your image and the blue side cannot see the blue channel.

So in photoshop we have to select the left image and remove red channel.
Select the right image and keep only the red channel (remove blue and green channel). Then modify the mode of the top layer into multiply. Which will produce the anaglyph 3D image and there you go.
See this image with your 3D glasses. If image is not appearing in 3D, reverse the glasses and check.

MEL Lesson 3 Conditions

The below condition checks the value of the above variable and returns (produces a result) a message in the output window (accordingly).


//--------- Declare Variable --------------
$yourCharacter= "good";

//------------ Condition ------------------
if ($yourCharacter == "good") {
print "You are my friend";
} else {
print "You are not my friend";
}

The below image illustrates what each line means

This condition can also have an additional "else if" added as below

if ($yourCharacter == "good") {
print "You are my friend";
} else if ($yourCharacter == "bad") {
print "I prefer to ignore you";
} else {
print "You are not my friend";
}

MEL Lesson 2 Variables

Execute the following 2 commands in the script editor.
$name = "ABC";
print $name;
Tip: If you dont know how to execute please see lesson 1.
Result:
ABC
Do you understand what is happening.
The print command is telling the output window to display "$name".
Since $name has the symbol $ as the first letter, the command understands it as a variable and looks for its value.
Since the value of "$name" is defined earlier as "ABC", the print command tells the output window to display "ABC".

MEL Lesson 1 Mel Basics

Print

Let us try a simple command to start with.
Just type the following in the "script editor"

print ("My Name is ABC.");

Tip: Read Mel Script Editor Getting Started if required

And execute this command by pressing "cntrl + Enter".
Alternatively you may press the "Enter" button in the num pad also.

Result:

My Name is ABC.

You have just told Maya to display the string "My Name is ABC." in the output window.

In this example "print" is called "command" and the string within the quotes is called "argument".

Voila! you are a Mel Scripter already.

MEL Lesson 0 Script Editor Getting Started

Open script editor from Menu> Window> General Editors >Script Editor

Or by clicking on the script editor button on the right side bottom of the screen

Script Editor looks like this

Type the command you want in the Input panel (bottom)

And execute the command by pressing the "Enter" button in the num pad.

Results of your command would be displayed in History panel (Above) of the Script Editor.


Tip: If you select your command before executing, your command will remain in the Input pane after execution, so that you can do any modification to it if required, other wise you may have copy it from the History Pane and put it in the Input pane to execute it again.

3D Character Animation

TRAINEE TO ANIMATOR checklist
The following steps can help improvise your animation.

1. REMOVE JERKS
1.1 Path of object:

After animation is done check the path your object is moving. (When I mean object I also mean differnt parts of the body). Onion skinning is not available in Maya, you may use a water based marker on your monitor to register each frame (beware some companies won’t appreciate writing on monitors with a marker) . Rectify any unsmooth path. Even though going through frame by frame and observing can show you the problem, using a marker helps you identify clearly where problem occurs.

1.2 Irregular spacing

Irregular spacing can create a jerk. Check frame by frame and space it regularly.

2. SPACING
2.1 Ease-out/ Cushion


Similarly spacing of an object requires you to onion skin (with marker may be) and check. It is usual to see some frames close to each and some far. Space it more regular. Having a 3 frame ease (cushion) at the end of each pose usually works. Dont forget overlap. Read Hit effect.

2.2 HIT EFFECT

When you want to get a hit feel. You need to space it in such a way that frames before the hit are even spaced and not cushioning before it hits. Ensure you squash the hitting object a little at the frame of hit.

3. BLINK

A 6 frame blink usually works fine. Overlapping animation for each eye also makes your animation looks beautiful. Have you eyebrow come down a little when the eyes are closed for added effect. Never have a frame without iris during the blink, ensure it is partially visible.
Blinks add life to character.
You may add blinks:
1. when a character changes the place he looks
2. when he/she is idle for a long time.
3. When head squashes

4. HANDS
When it comes to hands many animators take it for granted. Dont forget to delay the wrist and fingers during movement.

5. POSES
Animation is done to convey a story, attitude of you character is a key to achieve effective story telling.
Poses play an important role or rather most part of the role in getting the attitude of the character across to the audience.
If a character is angry for example you need to pose properly the eyes, eyebrows, shape of the mouth, shoulders, hands, elbows and overall line of action of the body. Many budding animators take hands for granted. The book "Acting for animators" says that hands are the most expressive part of the body.

6. MOVING HOLDS
No animation can be complete without a moving hold. Moving hold should never be significant, you are only trying to making it look unstable.

7. CHECKLIST
Most of the time animators know what is wrong with his animation when a mistake is pointed out to him. Animators should have a checklist in paper or even in their minds ask themselves whether they have animated the hands properly, are the blinks working fine, is it cushioning fine in the poses, is it space correctly etc..
All experienced animators do that.

8. CONCENTRATION
Unlike many jobs, animation requires continuous concentration. Regular breaks during works drastically slows down animators.

Pixel Aspect

A television stretches the input before it displays in a particular way. Due to this the input to the TV needs to be counter compensated (squeezed) before hand, so that the final output looks normal (unstretched).

Depth of Field in Animation

Depth of field is the region of focus of a camera.
The camera can focus only a particular distance from itself (which depends on the focus setting of the lens). The area ahead and beyond this focus zone gets blurred gradually. The range of this focus area can be longer or shorter depending on the setting (aperture) of the camera.

In 3D animation software such as Maya or Max, one can render a separate Z depth / L depth layer of the scene, which stores the distance information in greyscale (objects far from camera are rendered as black and closer in white or vice-versa). This z depth layer could be imported along with rendered images in compositing software such as Nuke or Fusion to produce the illusion of depth of field (A separate plugin may be required to tweak the level of blur and zone you want in focus).

Basics Photography

Exposure:
Three factors decide how your picture is exposed: A combination of Aperture, Shutter Speed & Film Speed.

Aperture:
Aperture setting determines the size of the opening of the lens or in other words, the amount of light that enters your lens. If you set a higher aperture (smaller F number eg: f4.5), your lens receives more light. Similarly if you set a lower aperture (higher F number eg: f22) you lens will receive less light.

Smaller Aperture:
If you have a small Aperture, less amount of light enters your camera, so you have to have a longer shutter speed to get enough exposure.
(Note: going lesser than shutter speed 1/40 secs will register your hand movement and result in a blurred picture)
Advantage of a small aperture is longer depth of field, which means range of focus will be more, which is usually preferred for landscape photography.

Bigger Aperture:
If you have a bigger aperture, more amount of light enters your camera. You may have to keep a faster shutter speed to avoid over exposure. Bigger aperture produces lesser depth of field, which means range of focus will be less (Only the object of focus will be clear). Good for portrait photography.

Shutter Speed:
This setting determines how long your lens is open. The longer the more light enters the lens.

Higher Shutter Speed:
High shutter speed is good to register fast action, sports etc.

Slow Shutter Speed:
Slow shutter speed is required during low light conditions. But it cant go lower than 1/40 of a sec as the camera will register camera shake.
Extreme slow shutter speed, with tripod, is good for registering the beauty of a night city.

Film Speed:
Faster films like ISO 400 or higher are more sensitive to lights and are good for shooting dim light situations, but grains will be more. ISO 100 produces clean photographs, but could be used in bright light conditions only. ISO 100 can be used in dim lighting condition by having long shutter speed using a tripod. But any objects which are moving in the view finder will get blurred.