Posted On: 2020-10-09
TRADITIONAL MAPPING vs. AERIAL MAPPING
TRADITIONAL MAPPING vs. AERIAL MAPPING
Maps are very important, Everyone understands and appreciates good maps. A geographic information system (GIS) is a framework for gathering, managing, and analyzing data. It analyses spatial location and organizes layers of information into visualizations using maps and 3D scenes. Maps are also the primary way that GIS users share their work with others in their organizations and beyond. Here are some traditional techniques used for mapping: High-resolution Satellite/Aerial Imagery: Many cities have high-resolution geo-rectified aerial photos available for them which can be used to aid mapping. Due to licensing concerns of the derived data, an individual should use only public domain imagery or imagery where this is explicitly allowed. This also aids in building the map later if one is using an editor that supports using aerial imagery as a background.
GPS Waypoints: GPS receivers make it very easy to mark waypoints. Usually, this method is used when accuracy is a higher priority with the data collection and time isn't as much as a factor but this can still be done quickly. One can use a notepad, or dictating-machine, to record what that waypoint corresponds to.
Digital Photography: Digital cameras are useful for recording street names, village names, and other features. Because digital photographs are time stamped, we can find out where the photographer was at the time (using their GPS log), and mark that as the photo location. Alternatively, we can use specialized software that will correlate our GPS log to your photos. The GPS information will be added to the meta-information inside the images. That way, an individual can programmatically have a list of places where one can take a photo.
Using paper: One can simply use a pencil and paper to map.
Field Papers: Field Papers is a web-based tool for easily creating a printable map for anywhere in the world that one can get printed and add notes to.
Video Recording/Audio mapping: Some mappers have found voice recording to be the medium of choice mapping. It's a form of rapid data gathering which leaves quite a lot of interpretation work to do later. There are a number of different audio mapping styles, with different accuracy, level of detail, which uses different hardware and software. For those driving alone who can't stop to take notes: mount a video camera (or digital camera in "movie" mode) somewhere that it can see road signs, and leave it recording for the duration of your journey. Then one can combine this with audio mapping (speaking road names and information into the video camera's microphone, e.g. "turning left into XYZ Drive").
Armchair mapping: This is a quite popular method, but it has several drawbacks like the fact that one cannot see names and much POI in the imagery. One can map without surveying in an armchair, interpreting aerial imagery, existing traces, and fixes problems reported in notes.
Online GIS: Online GIS can be treated by anyone using Web GIS and can be shared with virtually everyone.
Chain surveying: Chain surveying is the branch of surveying in which only linear measurements are made in the field. This is suitable for the survey of small areas with simple details and an area that is fairly flat. The principle of chain surveying is triangulation. This means that the area to be surveyed is spilled into a number of small triangles which should be well-conditioned. In this method, the side of the triangles is measured directly from the field using chain or tape without the use of any angular measurements. In this method, the check lines and tie lines control the accuracy of the given work. It is to be noted that plotting triangles requires no angular measurements to be made if the three sides are known.
For mapping a large area, traditionally it required a helicopter, plane, or satellite. The aerial data was collected by photogrammetric flights made by real planes. Those options are so costly and they require hiring people with specific skill sets. And one might be able to afford a flyover of a particular map-able area just once or twice a year.
Using classical methods there was a need for lots of people, lots of time, and lots of surveying instruments. But today, a few hundred bucks are enough to make anyone a drone owner. Now, mapping is just a matter of simply downloading the right software to the aircraft, and then taking it for an unmanned spin, a practice easily replicable on a far more frequent basis than the traditional alternatives.
"Drones" are one of the greatest technological successes of the 21st century so far, with Unmanned Aerial Vehicles (UAVs) now used for a range of commercial applications, whether it is parcel delivery or television filming. The phenomenal rise in usage of UAVs has led to the development of ever more sophisticated software, among which is 3D mapping software. The demand for high-quality aerial data captured from drones or UAVs is growing rapidly and now professional standard drones are easily available at affordable prices, and it's not just the big names of industries that are using them. The technology removes the guesswork when it comes to judging a range of data, and can potentially help us save time and money on our surveying project.
Mapping done using drones is carried out using a technique called Photogrammetry. Photogrammetry is the method of map-making or surveying by photography. The output of this technique called “Photogrammetry” is normally a map, measurement, or 3D model of a real-world object or scene. Most of the maps which we use today are created using this technique of photogrammetry and images clicked using aircraft. The capability of the UAVs to fly at fairly lower altitude compared to helicopters and aircraft, help in capturing higher quality images of the locations we aim to map.
When we use drones to capture images to make a map, our camera is mounted to the drone and is usually pointed vertically down to the ground. Multiple overlapping photos of the ground below are captured as the aircraft flies autonomously along a flight path that we specify beforehand. This ensures we don't miss anything and enough image overlap is achieved. This is the hard bit, if it was possible to do this manually the process could take years of painstakingly stitching and adjusting the images so they fit together and give a true orthographic view. Fortunately, there are now computers with respective software, to do this job for us. The software easily enables us to put together a comprehensive survey of land, buildings, and infrastructure and presents it in a variety of easy to manage formats. The best feature is the ability to take accurate measurements of length, area, and volume from the maps.
Aerial mapping has huge potential for a number of sectors including construction work, agriculture, mining activities, infrastructure inspection, and real estate activities. Having a clear, accurate photograph or 3D model of the project area, complete with measurements, is advantageous in terms of decision-making. Thus Aerial mapping is more advantageous than the traditional mapping method in terms of ease, cost, and the most important factor today which is time.
