Wayne Renshaw, Architect
commercial architecture
landscape & site design
rendering::rendering tips::column
  The Corinthian column represents a interesting modeling problem. It's important for the capital to look correct if the model is to be believable, however if you actually model the capital, you could spend the entire budget modeling the column alone--and your computer would spend all of its time rendering just the columns. Fortunately, there are methods that we can use that to simplify the process. These techniques require that the rendering software support multiple surface maps for a single texture, including a color map, bump map, and a transparency map.
surface maps
line drawing of Corinthian column
 I start this project by looking for surface maps--pictures that I will paste onto a simple model. For this project I found a simple line drawing of a typical Corinthian column capital. A photograph of a capital could have been used here, although it often difficult to find an photo taken from a similar perspective. Working from an illustration insures the proper perspective.
color the
shaded drawing of Corinthian column
 The next step is to color the illustration. For this exercise I took the analog route and used a pencil to shade the above illustration. The illustration was scanned, and adjusted for contrast. Since I have drawn this map in grey scale, I am using the same illustration for the color map and for the bump map.
texture maps:
ambient light
inverted silhouette of Corinthian column
 After scanning and adjusting the illustration, I created two additional texture maps. This map, which is simply a black and white image, is used as to tell the rendering program what the ambient lighting levels are around the column capital. Where white appears, the model will be lighted, where there is black the model will not be lighted. The black areas become a "black hole."
texture maps:
silhouette of Corinthian column
 The next map is called a transparency map. The black areas tell the renderer that this area is completely opaque, and the white areas indicate areas that are completely transparent. The program I used specifies this map as a grey scale map, so if we wanted to have areas that are somewhere between transparent and opaque, those area would appear as levels of grey (ie: 20% grey = 20% transparent).
build the model
diagrams of Corinthian column model
 Next, we build the actual model. The model itself is a simple box with wings. The wings provide a surface which dissolves away with the transparency map. Note that the top view has been exploded to show that there is a complete wing on each face. These wings actually touch on each side, as shown in the isometric view. (not shown is the shaft and base of the column...these are simple cylinders)
apply the maps

rendered Corinthian column
 Finally, we apply the surface textures to the the surface of each face and render. Be sure to set values for bump map, and set the transparency to full. Adjust the mapping so that the maps do not repeat, and are scaled to 100% of the size of the model. I have included a couple of simple renderings that demonstrate the final product: entire building (67 KB) and detail (58 KB)
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