LiDAR data collection is a form of remote sensing that measures how long it takes laser pulses to bounce off of objects and return to the sensor. Elevation may also be available in the form of LiDAR derived DEMs or as "point clouds" (LAS datasets). Today, LiDAR is becoming a popular data collection method for elevation. Traditionally, these DEMs were created using aerial photography and (less often) RADAR. The smaller the cell size, the more detailed the elevation data. The size of the cell is a very important consideration. Typically these will use feet or meters to represent the elevation. This representation represents the raster model and uses individual pixels, with each pixel assigned an elevation value. The other popular method of representing elevation in GIS is a Digital Elevation Model or DEM. More gentile slopes are represented by lines that are farther apart. Steeper slopes are represented by lines that are closer together. Contour lines follow a contour interval or the amount of elevation gained or lost in between lines. Contour lines are the vector representation of elevation and use isolines to connect areas of the same elevation. We encourage you to contact us if you have any suggestions.Įlevation is usually represented in one of two ways in GIS. Portions of this guide are still in progress. Still lost? Request data directly from us, from our collection or elsewhere, with our data request form, visit our AGSL GeoData homepage, or e-mail us with your questions.Start exploring or look at the tabs on the left side of this guide and click what sounds right for your project.The "Data Topics" box below contains commonly requested themes along with basic information on finding the associated data.
The "How To" tab contains tutorials on commonly used GIS procedures for suiting data to your particular needs.The sub-headings will take you directly to a guide for using a particular online resource.