Wayne Renshaw, Architect
commercial architecture
landscape & site design
rendering::rendering tips::virtual garden

  Modeling a plant is actually a lot easier than it might look. For this project, I photograph the plants and then use a texture map to place them onto simple models.
the plant
photographing a plant
 I begin the process by taking a few photos of some plants. To simplify the process of cutting out the background I placed a colored background behind the plant before shooting the picture. Any color will do, although it is best if the backdrop has a strong contrast to the thing you are photographing. (It would have been better to use a tarp that was not as shiny.)
strip out
the background
fountain grass with background stripped out
 Next, I cut out the plant's image in Photoshop. As there is a strong color in the background, all that I have to do is use the "select color range" Option under the "select" menu. The tarp reduces the cut-out task to just a few minutes of work. I also touched up the image by cloning some of the leaves to the other side of the plant.
grayscale copy
grayscale version of fountain grass image
 Next, I save a copy of the image in grey scale to use as a bump map. Be sure to blur the image as it helps to blend the greys, and provide a smoother bump map
silhouette of fountain grass
 This map is used as a transparency map. When the software renders the image, the areas in this map that are black are rendered, while the white areas become transparent.
ambient light
reverse silhouette of fountain grass
 The last map is used to control the lighting levels; areas that are black will not be lighted at all, and areas that are white are fully lighted. Both the transparency map and the lighting level maps can be grey scale maps, just in case you have areas that you want lighting and/or transparency that is somewhere between all or nothing.
plant model
diagram of plant model

rendered fountain grass
 The model for the plant itself is actually nothing more than a little "billboard" on which to map the textures. I usually place two small squares at right angles, as illustrated, this way, no matter what angle the plant is viewed from the eye will catch a major portion of the plant. I will normally make a named shape of each plant, and then populate the drawing with multiple copies of each plant.

All of these maps work together to produce the finished plant. Be sure to export copies of your plant shapes and textures so that you can use them in future projects.
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