The Visualization Toolkit (VTK) is an open source, freely available software system for 3D computer graphics, modeling, image processing, volume rendering, scientific visualization and information visualization. VTK also includes ancillary support for 3D interaction widgets, two and three-dimensional annotation, and parallel computing. At its core VTK is implemented as a C++ toolkit, requiring users to build applications by combining various objects into an application. The system also supports automated wrapping of the C++ core into Python, Java and Tcl, so that VTK applications may also be written using these interpreted programming languages. Since version 8.1.0, VTK requires the qt5 package. Version 8.2.0 is the last VTK suitable for Slackware version 14.2 due to the age of some SL-14.2 support packages (ncluding, in particular, cmake). Some optional additional packages, if detected during configuration, are used in preference to versions provided in the source code. These packages, available from SlackBuilds.org, are: jsoncpp proj You can enable a number of optional features by passing variables to the script (VAR=yes|no ./VTK.SlackBuild): IMAGING=yes|no (default: no) MPI=yes|no (default: no), requires openmpi TK=yes|no (default: yes) VIEWS=yes|no (default: no) WEB=yes|no (default: no), requires python-twisted JAVA=yes|no (default: no), requires jdk PYTHON=yes|no (default: yes) QT=yes|no (default: yes) VTK is an optional dependency for the opencv SlackBuild. However since VTK-8.2.0, it is not suitable as an optional dependency for opencv-legacy. The last suitable version of VTK for building opencv-legacy is VTK-8.1.2. Due to unmet build requirements (in particular, required cmake version), 8.2.0 is the last version of VTK which is suitable for Slackware 14.2.