This makes LiDAR particularly useful for mapping vegetated areas. One LiDAR emission can complete multiple returns, meaning it will bounce multiple times between the LiDAR system and any objects it meets. Unlike radar and sonar, LiDAR is not necessarily inhibited by object interference. Point clouds are highly detailed 3D maps, illustrating everything from a downtown core to a national forest. The map of the United States would be the non-topological data, while the drought conditions data would be the attributes. Topological data isn’t just limited to linear data such as elevation.ĭrought conditions in the United States are a good example of a map that could be stored and shared as a shapefile. The non-topological data (x,y coordinates) illustrate the base terrain, while the associated attributes (z coordinates) represent the elevation profile. It consists of x,y coordinates and does not include a third dimension (the z coordinate).Įxamples of non-topological data include street, state, or area maps.Ĭonsider an elevation map. To breakdown what that means, let’s return to our original definition of GIS: the intersection of data and location. Shapefiles combine non-topological data with associated attributes. Shapefiles are, by far, the most common GIS file type.ĭeveloped by GIS powerhouse ESRI, shapefiles are a simple way to store and share GIS vector data. Continuous rasters are often used to represent data that experiences gradual change: temperature, population, elevation, etc. In contrast, the map on the bottom represents continuous data.Įach grid cell contains some level of gradation. The map on top illustrates discrete raster data.Įach value is assigned a different color, while each cell has only one data type and one color: there’s no gradation of either. In fact, most people’s height is not exact to the inch or foot.Ĭontinuous and discrete data are complementary, but do have different applications. A person's height can be any value within the range of human heights. You’re limited to whole numbers: no decimals or percents.Ĭontinuous data is more flexible, including values such as height, weight, and length. You can have any number of people, but you can’t have half a person. The number of people in a room is a discrete value. In terms of GIS mapping, raster data comes in two types: discrete and continuous.ĭiscrete data can only take specific values, whereas continuous data can take any value within a range.
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