I have to apologize because somewhere I said that the picture needed is Mercator.
This is not true Cylindrical panorama picture is needed.
FMS_PL
FMS_PL can produce perfect FMS Landscape, if the picture is for Cylindrical mapping and because of two pixels overlapping 8176 *2046 pixel picture size should be selected (76,3° angle of view and about 4:1 aspect ratio).
The good feature of FMS_PL that it can produce 2*8 pictures.
FMSXYZ
First of all FMSXYZ is for displaying and moving objects. If the picture mapping is relative and therefore Position command is used the objects are displayed even if FMS Landscape is panorama type.
The mapping planned is Cylindrical, but overlapping is needed otherwise white stripes are visible between pictures therefore I am taking the mapping and pictures from FMS_PL.
The sky should not be square therefore mapping of the sky picture is needed, for the time being a quarter picture is mapped to the top matching to two faces of the eight sided cylinder.
The sky panorama picture should be circular, the matching of the circular cylinder and the circular picture of the region around the zenith in principle should be perfect.
In practice the approximation error is too big. Therefore my next effort will be the elaboration of a 32 sided cylinder and the appropriate sky picture mapping.
If anybody is interested the Telki_Cylinder FMS Landscape can be downloaded and the quality checked.
http://www.sztaki.hu/~csaba.laszlo
I don’t know converter program which can convert equirectangular picture (reflex) to 76,3° Cylindrical. Therefore only those can use cylindrical mapping who are stitching the panorama picture themselves. If equirectangular picture is used there is a distortion about 20%.