blots on wall

[Luc_kriva]

Hi, please can you give me advice how to clear the render? I know it is caused by lighting ... I have used only hdr environment light because it makes the best shadows ... The rendering time was set for 3 hours so I dont think it could be caused by short rendering time...or could?

[DMerz III]

Are you using the 'Interior' mode? That usually works better with enclosed spaces like this. If you are, then you probably need to let it cook a little longer or up the sample rate, depending on your desired settings. Also, HDR alone would mean all the light is coming through the window? Have you tried placing any physical lights inside the space and seeing if that helps? These ideas might not solve your issue or work for the 'look' you're trying to achieve, but those would be my starting points!