iWitness 1.4 could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. We recommend checking the downloaded files with any free antivirus. The actual developer of the program is Photometrix Pty Ltd. IWitness.exe is the frequent file name to indicate this program's installer. The most popular versions among iWitness users are 2.0 and 1.4. The program lies within Photo & Graphics Tools, more precisely 3D Design.
From the developer:
iWitness is the most robust and user-friendly close-range photogrammetry software available for creating three-dimensional measurements from photographic images. A complete measurement system for 3D scene reconstruction now needs only a consumer-grade digital camera, a PC and the powerful, inexpensive iWitness software.
You may want to check out more software, such as iWitnessPRO, which might be related to iWitness.