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Aerial project photograph of a complex Belgrade Bypass interchange, showing multilayer road infrastructure and surrounding terrain.
FLAGSHIP INFRASTRUCTURE MAPPING

Belgrade Bypass Sector C — Digital Topographic Foundations

Airborne LiDAR, photogrammetry and verified 1:1,000 engineering topography for a complex road–rail corridor

Controlled airborne reality capture transformed into verified 1:1,000 engineering data for Building Permit Design.

LocationBelgrade Bypass Sector C, Krnjača railway station and the Pančevo–Alibunar railway; the documented final realization covers approximately 3,400 ha
Direct clientSaobraćajni institut CIP d.o.o., Belgrade
Project period04.2023 – 06.2024
MapSoft roleDirect geodetic-photogrammetric contractor
Project context

A road–rail design corridor that demanded one controlled engineering reference

Sector C combines planned road and railway geometry, existing rail infrastructure, Krnjača station, peri-urban terrain and major transport connections. MapSoft's contracted task was to establish a common, high-resolution geospatial foundation for Building Permit Design, not a collection of isolated survey outputs.

~3,400 haDocumented final realization area
4 / 129Airborne missions / realized flight lines
5 cm/pixelOrthophoto GSD
1:1,000Engineering DTM & DTP

MapSoft’s documented scope covers geodetic-photogrammetric acquisition, processing, QA/QC and engineering-data production for the corridor. Wider road and rail design or construction works were outside MapSoft’s scope.

01

Establish field control and project-coordinate transformations

02

Plan and execute synchronized airborne missions

03

Process trajectories and adjust LiDAR strips

04

Perform aerial triangulation and photogrammetric restitution

05

Build DTM/TIN and 5 cm orthophoto

06

Produce and validate 1:1,000 CAD-ready DTP

Field control

Quality started on the ground — before the aircraft flew

The final realization report confirms 41 photo-signalled GCPs and 84 LiDAR control-field points at five locations. Planning, materialization and static GNSS measurements created the independent control needed for georeferencing and later validation.

Project planning map with ground-control points, LiDAR control fields and corridor coverage prepared before acquisition.
Ground-control and LiDAR control-field plan
Close view of a permanently marked and photo-signalled ground-control point used to connect airborne data to field control.
Photo-signalled ground-control point
MapSoft field surveyor performing static GNSS measurement on project control.
Static GNSS measurement — control point 3
Airborne acquisition

Synchronized LiDAR and RGB acquisition across multiple infrastructure areas

Four airborne missions and 129 realized aerial-photo flight lines connected the distributed project areas into one production workflow. Acquisition geometry, coverage and control distribution were documented and checked against the planned mission design.

4airborne missions
129realized aerial-photo flight lines
LiDAR + RGBsynchronized airborne acquisition
Realized mission-line plan showing the distributed flight geometry required to cover the road, rail and station areas.
Realized airborne acquisition plan
SILA 750 aircraft used as the airborne platform for the documented LiDAR and RGB acquisition missions.
SILA 750 airborne survey platform
Trajectory QA

GNSS/IMU trajectory quality was checked quantitatively throughout processing

Trajectory processing was reviewed through solution status, satellite availability and smoothed position RMS. The final report states a fixed solution for the complete trajectory; representative smoothed RMS is approximately 0.015 m horizontally and 0.024 m vertically.

Fixedcomplete trajectory solution
~0.015 mrepresentative horizontal RMS
~0.024 mrepresentative vertical RMS
GNSS QC summary with satellite availability, PDOP and solution-type statistics for trajectory processing.
GNSS quality-control statistics
Mission chart showing total and constellation-specific satellite availability through time.
Satellite availability during the mission
Smoothed north, east and down position-error RMS traces from trajectory processing.
Smoothed position error RMS
Photogrammetric QA

Block geometry and aerial triangulation were verified against field control and tie points

Four photogrammetric blocks were adjusted using ground control and tie points. Exterior-orientation and tie-point error-ellipse views make residual behaviour visible instead of reducing QA to a single pass/fail statement.

Graphical representation of error ellipses for estimated exterior-orientation parameters across the photogrammetric block.
Exterior-orientation error ellipses
Graphical representation of tie-point coordinate error ellipses used to inspect photogrammetric-block quality.
Tie-point coordinate error ellipses
LiDAR strip adjustment

The strongest visual proof: relative consistency, absolute control and geometric refinement

The QA chain combines sensor self-calibration, tie-plane accuracy and distribution, roof-line and plane-intersection checks, and height-difference mapping. Final-report roof-line RMS ranges are 0.015–0.020 m horizontally and 0.007–0.014 m vertically.

Height-difference maps show that most hard-surface cells remain below 0.02 m, while larger differences are mainly associated with vegetation and vertical objects. Reported values are limited to validated QA results.

0.015–0.020 mroof-line horizontal RMS
0.007–0.014 mroof-line height RMS
< 0.02 mdominant hard-surface cells on height-difference maps
Strip-overlap homogeneity visualization from project QA material.
LiDAR height-difference QA
Cell-based height-difference map used to inspect local strip-to-strip agreement and isolate larger deviations around vegetation and vertical objects.
Detailed height-difference map between overlapping strips
3D inspection of matched roof-plane edges used as a high-contrast geometric test of strip alignment.
Extracted roof-line edge analysis
Sensor polynomial correction curves used in the LiDAR self-calibration and refinement workflow.
LiDAR sensor self-calibration corrections
Tie-plane separation statistics used to quantify relative LiDAR strip consistency after refined processing.
Accuracy verification at tie planes
Tie-plane distribution histogram used to assess the angular support of the strip-adjustment control geometry.
Tie-plane distribution by scan angle — project QA
Edge-separation analysis generated from intersecting planar surfaces during refined LiDAR strip verification.
Plane-intersection edge analysis
Engineering products

Verified measurements were converted into terrain and CAD-ready topography

LiDAR-supported terrain modelling, stereo restitution and cartographic processing produced a 1:1,000 DTM/TIN and detailed DTP. The final product views show the level of engineering detail used around interchanges and developed corridor areas.

Matched 2D/3D view of the georeferenced LAS 1.4 corridor point cloud.
RGB-colourized LiDAR point cloud
Completed terrain structure with characteristic breaklines and engineering geometry.
Final DTM / TIN engineering model
Publication-safer crop of the completed DTP showing road/rail geometry, terrain and engineering content.
Final 1:1,000 digital topographic plan
Detailed topographic-plan view showing terrain contours, buildings, roads and corridor-related engineering content in the Vrčin area.
Detailed 1:1,000 DTP — Vrčin area
AutoCAD production environment showing detailed road-interchange geometry and terrain/topographic linework prepared for engineering delivery.
CAD preparation of the final DTP
0.043 mDTM control standard deviation, 10 points
0.019 / 0.020 morthophoto RMS Y / X, 12 control points
5 cm/pixelfinal RGB orthophoto
1:1,000DTM and DTP engineering scale
Delivered outputs

A complete chain from field control to final CAD-ready data

01

RGB-colourized georeferenced point cloud

Final adjusted airborne LiDAR with point attributes.

LAS 1.4
02

Digital Terrain Model

Engineering terrain model produced from LiDAR ground/model points, stereo restitution and TIN editing.

1:1,000
03

Digital orthophoto

Current RGB image base for the documented project area.

5 cm/pixel
04

Digital Topographic Plan

Detailed CAD-ready topography in eight thematic groups.

1:1,000
05

Ground-control, mission and QA documentation

GCP, flight/scanning, GNSS/IMU, density, strip, AT, DTM and orthophoto QA records.

Documentation
What this project proves

Belgrade Bypass Sector C proves MapSoft can act as the direct specialist contractor for a large infrastructure mapping package, integrating field control, airborne LiDAR/RGB, direct georeferencing, photogrammetry, terrain modelling and rigorous QA into design-ready engineering data.

Belgrade Bypass Sector C is a particularly strong MapSoft reference because quality control is visible throughout the complete production chain: control on the ground, mission and trajectory checks, photogrammetric block verification, LiDAR strip refinement, DTM and orthophoto validation, and final DTP geometry/topology inspection.

Ground ControlAirborne LiDAR + RGBGNSS/IMU QAStrip AdjustmentAerial TriangulationDTM / Orthophoto1:1,000 DTP

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Need engineering geospatial data where the QA trail matters as much as the final map?

Talk to MapSoft about controlled airborne LiDAR and photogrammetry, ground control, trajectory processing, strip adjustment, terrain modelling and CAD-ready topographic production for major infrastructure.

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