Advantages and disadvantages of LiDAR

Jakarta – A quotation email – Co R. Raharjo

A. Although current LiDAR technology is technology that is quite sophisticated in providing data topo, could explain advantages and disadvantages of LiDAR base on your experience Pack ?.

Agree Sir, more technology here more ' cutting edge '. The advantage of using LiDAR and Photogrammetry for the manufacture of topo maps, among others:

1. LiDAR manggunakan waves on so that the laser can do acquisitions night. But since in the package now include LiDAR system with sensor camera (passive wave) that can only be good workers at noon, the acquisition can only be done during the day so that both the sensors can work.
2. LiDAR system can perform the acquisition of millions of points x,y and z in elevation per hour is much faster compared to conventional motede (ground survey).
3. The density of the point/point of ground generated per 1 min. sq meters 1 point but can be up to 9 point depending on the surface and flying high (acquisition methods) as well as the FoV (Field of View/sensor viewing angle to Earth). Pulse tools quantity not so affected, currently there are vendors who are able to make tools with pulse LiDAR above 500kHz, This major will be a maximum pulse if the retrieval/data acquisition with aircraft could “fly high”. For the tropical country of Indonesia where cloud altitude 1000 s/d 1500 FT, then the aircraft will fly under the clouds. To fly with the height under 1000 FT, It is enough to use pulse 75-120 kHz and FoV 18 s/d 25 deg.
4. Because it uses an aircraft, easier access course for the acquisition/reach into every part of the site. And beside that, be able to avoid direct contact with the public, that is a big problem on the survey ground / conventional survey.
5. It only took 1 ground control point (BM) for the flying radius of acquisition 30 sd 40 miles from the ground control point.
6. The aim of vegerasi entrance Mampung, because of its wave character such as ultraviolet waves and use shorter wavelengths of the electromagnetic spectrum which is around in nm 1064.
7. More efficient and cost effective, If area > 1.000ha. Ground Survey to 1,000 ha may 1, 5 m to 2 m, If either using LiDAR systems under 1 m.

1. LiDAR Sensor system is not bekerjaan a maximum if the cloud/fog hindered.
2. Pulse is not reflected properly if wet, reflective objects (watery). Due to the Topographic LiDAR pulse will be absorbed / lost if the water such as rivers or pemukaan wet akhibat dew or rain. Hydrographic LiDAR is used to contrast with Topo, for Hydro, known as SHOALS or stands for Scanning Hydrographic Operational Airborne LiDAR Survey. This System is able to acquire the water level and water depth 50 s/d 60 metres from the surface of the water.
3. In conditions of vegerasi are very closely "any Sunshine" could not enter on the sidelines dedaun, then certain pulse LiDAR also won't be able to go down to the ground (land).
4. LiDAR data accuracy or the resulting LiDAR ketelitiaan price, relies heavily on the surface condition: open software, Open hardware, Bush beluka, swamp forest, hard woods, virgin forests and others. For hard ketelitan open area can attain under 5 cm. Horizontal Precision 2 time s/d 5 times more “ugly” from the Vertical precision of. If there is a need for data comparison between LiDAR and ground surveys for various surface conditions such, can contact me thru admin lidar indonesia: info@lidarindonesia.com

B. In some cases, Our difficulty in data between the topo overlay, often not ' matching ' each other, especially the elevation data. Kira2 what causes her ? and how to overcome those things did not happen so ?.

1. Different coordinate systems are used to each other, that is the point of zero for x,different between y and z data.
2. Not on an equivalent data quality, It means the data 1 have an accuracy +/- 1 While that FT 1 longer has pinpoint accuracy +/- 5 FT.
3. Shared reference point (reference data) not at a stable position. Akhibat the movement of the ground reference point can be shifted to 0,15 meters or even 0,5 FT, especially the ' vertical ' move in its annual.

1. Make sure all the work associated with the position of survey/coordinates using the same koordinaat system (reference point 0 for x,y and z are the same) and quality of ' accuracy ' of equal. For example, the data will be in the borehole position overlay data with topo LiDAR results (contour/dtm), LiDAR data has an accuracy of 10-50 cm, borehole position data accuracy should also be within the range of these numbers or vice versa.
2. Be sure to use the same reference BM for each measurement. If missing then the references need BM pulled/re-measured from the point of the same previous BAKO DONATIONS.
3. Make sure the position of the reference on the area of BM ' stable ' land geology.
4. In the case of overlay contour contour and LiDAR survey ground often not macth. Conceptually, contour interpolation is the height of the high-points of the ground gained or produced good survey LiDAR and ground survey. Contour interpolation will be getting closer to actual conditions if points of high ground are presented very close and good quality. Talk to the quality/accuracy of point/position, survey ground ' better '. But for the density of LiDAR survey was able to provide the high points of the meeting from the very ground survey ground due to difficult ground surveys do observations of the high points of the LiDAR serapat due to constrained distance minimum of ' kekeran ' tools….. (dialled again later..)

While this used to be, hopefully helpful…. amin

Greetings
R. Raharjo – Lecture and Observer LiDAR