ltview − view photometry of a light source
ltview [ −i ][ −b boxsize ][ −o device ] input
ltview renders a Radiance luminiare or IES photometry interactively using rad(1).
ltview accepts exactly one Radiance object or IES photometry file as input. No input is taken from STDIN. The −i option tells it that the input file contains IES photometry rather then a Radiance description of a luminiare. In this case, Radiance’s ies2rad(1) is called with its default settings to convert the IES file into a Radiance object.
Unlike objpict(1) or objview(1), no additional light sources are added to the scene, since it is assumed that the object is a luminaire.
ltview relies on Radiance’s rad(1) command to compile an octree using oconv(1) and to call rvu(1) to display an interactive preview of the luminaire. The luminaire, or output from ies2rad(1), is moved so that its center is at world origin. ltview then generates an open box around the fitting that is ten times as big as the largest axis−aligned dimension of the fitting. The −y face of the box is left open so that the camera can look inside, facing +y. The overall dimensions of the enclosing box may be overwritten with the −b boxsize option. Note that both the fitting and the box are always centred at the origin.
When ltview is run with the −i option, i.e. the file is an IES photometry file, then the dimensions of the luminaire and intesity of its output are determined by ies2rad(1)’s default settings. If this is not acceptable, then it is best to run ies2rad(1) manually, and to feed ltview the hand−crafted fitting, rather than the IES photometry. In any case, it is likely that the initial exposure within the rvu(1) window window needs to be adjusted before the distribution of the fitting can be fully appreciated.
The default rvu(1) output device is x11 on all platforms except for Windows, where it is set to qt. This may be overwritten with the −o output option.
To query available output devices
To visualise an IES file with the qt driver
ltview −o qt ABC123.ies
To look at a typical fluorescent fitting that is modelled in millimeters
ltview −b 5000 XYZ_batten.rad
ltpict(1), ies2rad(1), oconv(1), rad(1), rvu(1)