Replace a string using textport in Houdini.

It is easy to change, for example, $HIP to $JOB for a whole scene by using textport

opchange -p / \$HIP \$JOB
opchange -s -i "asd" "qwe"

-p <path>
Start searching from this path in the operator hierarchy. If
you don't specify a path, the search begins at the root (/).

-s
(Silent) Do not print the list of changes.

-i
Normally, <from_string> only matches whole words (for
example, string "myobj" would not match value "myobj1". You
can use the -i flag to make the string match word
substrings.

Linking light to a camera.

Camera linker helps with positioning of lights according to camera position. Especially it works well with distant(infinite) lights. Light needs to be connected to the camera linker.

By default, camera linker works in the world space. Once needed camera is selected in the ‘camera’ field, camera linker will work in camera’s local space.

If there is a big camera movement, the light will follow the camera and shadow direction will be changing all the time.

camera_linker_v03

In order to avoid this, it is better to freeze light position in specific frame. There is the ‘Static Frame’ option, which freezes light position in current frame. Of course, it is possible to change the frame.

camera_linker_v04

There is also ‘Ignore Camera Tilt’ option, which switches vertical axis Y from the camera space to the world space.
If camera’s tilt is changing dramatically, it’s better to lock it - turn on ‘Ignore camera Tilt’.

Ignore Camera Tilt - off

Ignore Camera Tilt - off

Ignore Camera Tilt - on

Ignore Camera Tilt - on

This is the simple asset. It contains just few nodes. CHOP network grabs the information about camera position and rotation. Then, there are few blend nodes that help to mix and switch local and global transformations. Nothing special, but it helped me a lot during lighting process of tv series.

 

Download: obj_camera_linker_v001.otl