Lifta Historical Village Survey
150 office days instead of 300 days using Total Station or 360 using scanner
Israeli historical authorities decided to re-establish ancient buildings of historical village near Jerusalem as a tourist area:
The task was to survey a big area of 80,000 [m2] (20 acers) with high steep slopes and 121 ancient buildings, creating 3D topographic map in 1:100 scale.
In addition, 3D building reconstruction, including 3D building contours, Façades, roofs mapping, 2D sections.
Using conventional surveying techniques, entailed several major challenges: safety, complex structures and obstructions.
The estimated effort using conventional surveying techniques reached 600 field Days and 300 office days:
- ~ 600 (121*5) field days, 5 field days for each building, total 121 buildings, using a crew of two people using Total Station measurements and RTK.
- ~ 300 office days, 2.5 office days per building to create a CAD model per building and its area, utilizing Total Station and RTK measurements and a field sketch.
The estimated effort using Laser Scanning:
- ~ 121 filed days, a field day per each building, using a laser scanner from several scanning positions.
- ~ 360 (121*3) office days, 3 office days to create a CAD model per building and its area, utilizing the laser scan data.
A regular Sony Nex-7 24MP camera was used. The camera was mounted on a UAV DJI S1000.
The area was divided into 121 sections and each section was photographed in a circle pattern.
Control points were surveyed using a Total Station
The actual effort to survey and create an accurate 3D CAD model was 180 working days (instead of 900 using a TS, and 481 using laser scanner):
- Total of 30 days in the field (instead of 600 using TS or 121 Laser scanner)
- 27 field days to set targets, survey them and measure 1815 control points in the area. Control points were measured using a prism-less Total Station device (15 GCP per section, 15*121= 1815).
- 3 field days to photograph the site using a UAV.
- 150 office days (instead of 300 using TS and 360 using Scanner) to geo-reference the data (overall 121 DatuGramTM3D projects), generate an accurate 3D CAD model, and create more than 30,000 new 3D points.
- The project revenue was 550,000$ while actual work cost was only 53,000$. The project’s net income, using DatuGramTM3D, was 497,000$.
3D CAD model in DXF format was created. It included the area topography, building’s Façade and roof that were generated by drafting directly on the images using DatuGramTM3D.
A point file, including names, codes, descriptions and coordinates of all new points, was also generated. Overall, more than 30,000 new points were drafted directly on the images.
A 2D Façade plans including ortho-photos were created for each building.
The measurement accuracy of all the points was better than 2 cm (0.065 ft) in both position and elevation.
Topographic CAD map: