Autodesk 12812-051462-9011 User Guide 3 - Page 2099

NOTE Each saved attribute or channel must have a unique file tag. If you specify multiple instances of a file tag, only the first attribute or channel with that file tag is used. ■ All the current attributes are String type attributes that are stored in the header for the file, and can be read in plain text via the exrheader.exe utility (available from http://www.openexr.com/the official Website > Downloads page). ■ Attributes and channels are stored in the file in alphabetical order according to the ASCII file tag. ■ While this plug-in can write most of the 3ds Max G-Buffer on page 7991 channels, there is no software that can utilize them yet. ■ Attributes and channels are identified by plain-text (ASCII) strings. There can be only one instance of a string tag in any file. Attributes are data that is stored per frame, not per pixel, and they are embedded in the file's header. Channels are data that is stored per pixel. In order to maximize flexibility with other software, this plug-in lets you edit the file tags. You should only do this if you know the tag required by some other software; otherwise it is best to leave the file tags at their default values. ■ Channels that create multiple "slices" in the EXR file require multiple file tags. In this case, the file tag in the user interface comprises several sub-tags denoted by square brackets. For example, the Normal channel generates three slices in the EXR file: one for the Normal vector x data, 1 for y, and 1 for z. In this instance, the tag string in the user interface would read [NX][NY][NZ], and generate slices with the file tags "NX", "NY", and "NZ". The file tag is used by software that is reading the EXR file to identify the intended use of the channel data. Even standard image channels are encoded this way, with the tags "R", "G", "B", and "A" used to denote red, green, blue, and alpha channels respectively. Extended Attributes Comment A general-purpose comment string defined by the user. To define the comment, highlight the Comment entry in the list and then edit the Comments field immediately below the list. Computer Name The name of the computer the image was saved from. In the case of standard render output during a net render, this is the machine that rendered the frame. System Time The UTC (GMT) system time and date when the file was written. 7354 | Chapter 23 Managing Scenes and Projects