You could do it with Bryce, but it depends on the detail you provide. By default, Bryce will generate a random white image on a black background and use that to generate a mountain, thus the term "landscape", and you can modify the mountain in a myriad of ways. But you can also import any greyscale image and Bryce will use that to generate a landscape. Therefore, depending on what kind of image you import, you can make a mountain or any number of custom shapes, 3D text, architectural elements, etc. Check out my "Planet Eben" thread. The last two images are a height map of the continents done in Photoshop and then a 3D terrain using the same height map image. I might try doing a high resolution height map later.
http://www.cartographersguild.com/fi...anet-eben.html