black reflections with vray sun

[fareen]

i have been working with vray sun from quite a while but one thing always troubles me.

 

the bg in the scene with sun and vray cam doesnot turn up unless u uncheck the affect bg in colour mapping, and even if u do uncheck it the reflections on the glass comes black, the method i use to over come this is to put a hdri in the environment with a very high value like 80 or 100 and check the affect bg . this way i get the reflections also on the glass and also the bg is visible. But when i want the reflections of an image on the glass, in a regular light and cam i extrude an arc around the building and apply the desired image to reflect on the glass, in case of the sun and vray cam the glass does not reflect the extruded arc how do i use the sun and vray cam with correct reflections on glass with out having to increase the hdri value in the material editor, in this method i am resrticted to only use the hdri maps and cant use a normal image since i cant increase the light multiplier. Can any one please help me with this, or atlest tell me how to get the reflections of an image mapped on an arc on to the glass when using a sun and vray cam.

 

Thanks

[AJLynn]

The problem is that the sun is at a physically correct brightness and the background image is not - the sun is so much brighter that you use some exposure system to compensate, and the exposure system makes the image dark. Try putting the image as the map in an Ouput shader instead of a Bitmap shader and cranking up the Output shader's RGB Level, or using only HDRI graphics (good ones, not the crappy ones you find sometimes that don't have high enough bright values) with levels set appropriately.

[JamesTaylor]

yeap, i second andrews comments - you should be able to use any bitmap but you will have to crank up the output value

[fareen]

thanks i shall try that i never tried boosting the rgb value in the material editor