Converting a TiB (Tebibyte) to ISO exclusively isn't directly possible because TiB is a unit of digital information (like a megabyte or gigabyte), while ISO is a file format used for disc images. However, I assume you're asking how to convert a file or data from a TiB (which seems to be a misunderstanding since you can't directly convert a unit of measurement to a file format) to an ISO file, or perhaps understanding the conversion in the context of data sizes and then creating an ISO image from data.
: Copy the files you want to include in your ISO from the mounted backup to a temporary folder on your local drive. Create the ISO convert tibx to iso exclusive
If you want to create an ISO image from a folder or a set of files (not directly from a unit of measurement like TiB), here's a general guide: Converting a TiB (Tebibyte) to ISO exclusively isn't
Before we begin the exclusive conversion process, you must understand the architecture of these files. TIBX is a file-system agnostic container
Converting TIB to VHD Files Using Acronis True Image Home 2010
Notes on implementation in specific languages