LiDAR surveying, which stands for light detection and ranging surveying, is used in numerous applications. LiDAR detection systems work the same way radar does, but instead of sound, it uses light to transfer data back to the source. Many people confuse light detection and ranging for photogrammetry, although many of the applications are similar.
While the two surveying technologies are similar, they are actually quite different and produce two very different results.
LiDAR Versus Photogrammetry
LiDAR, as stated above, uses light in the form of lasers to gather information. The technology works by emitting lasers and measuring the time it takes for the light to return to the source. It’s considered an active sensor because it emits its own energy source rather than reading sources from the ground. Photogrammetry gathers data by analyzing and comparing multiple two-dimensional images (photographs) to create a three-dimensional model. It’s considered a passive sensor because it does not produce its own energy source to gather information. Whereas liDAR technology produces its own light to create images and measurements, photogrammetry is limited to gathering data based on what the camera can detect with ambient light.
Both liDAR surveying and photogrammetry can be used to take measurements and discern data, but they have very different products. LiDAR creates a three-dimensional model by bombarding the target with lasers. The frequency of the scan and repetition rate will determine how dense the image appears to be. Imagine a 3D-image that is painted by an artist using pointillism (the act of using small dots in various patterns to create an image), but with one color. LiDAR doesn’t differentiate color, although adding false color after the scan is complete is possible to help interpret the result. However, adding color to the image can be as difficult as trying to interpret the initial monochromatic version. Photogrammetry, on the other hand, produces a fully-colorized 3D image by “stitching” together multiple 2D photographs, although it can take thousands of photographs to get an accurate model.
So, if the specific requirements of the surveying job require high levels of visual interpretation, then photogrammetry might be the optimal choice. If the target object is covered by vegetation, then light detection and ranging will be better equipped for the job since the lasers can penetrate canopies and vegetation.
If your job requires either of these services or any services of a reputable and professional civil engineering company, then call us today.