Bandolin, that is one of the great things about Bryce. You can use not only the cloud filter in Photoshop but you can export an entire Bryce tiled height map, work on it in other image editing programs, create your river right onto the height map, then re-import it back into Bryce and continue working on it. You can even create different standard terrains in Bryce with totally different features on it export them all out as height maps and in any editing program, weave them together to create an entirely different landscape. Importing images into Bryce to create images isnt anything new to Bryce, if you have Susan Kitchens book (the Bryce bible) you can read about this Bryce feature starting on page 675 Altitude Render. But the original topic to this thread before it veered off into different directions was about Bryce tiling and thus yet again we veer off into importing and exporting height maps. Two totally different topics. You cannot compare height map generation with mathematical algorithmic generation. The fractals that Bryce puts out as natural geographical geometry come from algorithms developed and exclusively engineered for that purpose, to make them look like mountains and natural landscapes. The scientific works of Ken Mustgrave who worked with Benoit Mandelbrot (of Mandelbrot fractal fame) at Yale university and Ken Parlin (now Parlin Hills in the fractal type generator) were married together by software engineer, musician, artist Eric Wenger (the son of a geologist) into a software package for his personal pursuit, which we now call Bryce. You can read more about the history of Bryce starting with chapter 1, page 1 of Susan Kitchens book. Bryce can bring any outside image into its interface and treat them as height maps, including other fractal images. You can even handwrite your name and bring that into Bryce. But that doesnt mean that those images will look as natural as the fractals engineered to serve that purpose by the original creator of the program. Not all fractals are engineered to look like natural. For instance, although the accompanying fractal may render interesting in Bryce, it is far from anything geological. That feature to import outside images from what I understand, wasnt developed until later when it became public and not inherent in the original software. What would be really nice is if new algorithms were further developed to enhance the Bryce experience.