Lifta Historical Village Survey

Job TypeLarge scale topography and structures survey project
CompanyGeoPoint Ltd
CountryIsrael
Project Size80,000 m2 (20 acers)
Number of images3600
Accuracybetter than 2 cm (0.065 ft)
DatuGram3D savings30 field days instead of 600 days using Total Station or 121 using scanner
150 office days instead of 300 days using Total Station or 360 using scanner

project description

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.

data acquisition

lifta-case-study1

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

 

 

DatGram™3D Savings

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$. The project’s net income, using DatuGramTM3D, was 497,000$.

lifta-case-study-table

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Achieved Results

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.

Building Façade:

lifta-case-study-facades

lifta-case-study-facades1

 

Roof Plan:

roofplan

Topographic CAD map:

topographic-cad-map