mesa was rebased in RHEL 7.2, causing vtk-6.1.0-4.el7 to fail to rebuild. This was fixed in Fedora commit 107f95b.
vtk-6.1.0-5.el7 has been submitted as an update to Fedora EPEL 7. https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2015-5126537f6d
vtk-6.1.0-5.el7 has been pushed to the Fedora EPEL 7 testing repository. If problems still persist, please make note of it in this bug report. If you want to test the update, you can install it with $ su -c 'yum --enablerepo=epel-testing update vtk' You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2015-5126537f6d
vtk-6.1.0-5.el7 has been pushed to the Fedora EPEL 7 stable repository. If problems still persist, please make note of it in this bug report.