–click for larger image–
Performing a Slope Density Study is commonplace in Los Angeles County unincorporated areas for land development. It determines the number of allowable lot subdivisions can be extracted from a larger lot in a hillside area. I am able to obtain topographic data from Los Angeles County LIDAR data at a very minimal cost (far less than the cost of performing an actual site survey) that is quite acceptable for these studies. After that, I am able to create a 3D model of the surface within the lot and then perform the actual study. In most cases, the surface model gets used for hydrology and preliminary grading studies anyways so if you're developing a lot in the LA area, the same terrain model is used multiple times. The example shown here is a somewhat special example due to the fact that two separate areas needed to have individual slope density studies so I had to create two distinct color schemes for the plan to be easy to understand.