Well no, I brought the Revit render into the origional photo because that is the location of the building, so I wanted to make the Revit model look like it fitted on site. So cutting out the straight lines of the Revit model is easy in photoshop. But it is/would not be hard to do it theother way around. Photoshop has some neat tools like the magic wand (don't we all want one of those), you can adjust the amount of pixels it picks & the frequency so you just follow your pointer around the image & the outline as you dictated is automatically chosen. Using a tablet would make it even easier. if it was a really difficult image you could do it in bits & use photoshops layers to put the bits back together again.