3D model of a historic district park on the Auraria Campus, Denver

Point cloud and textured 3D mesh of Denver's 9th Street Historic Park from 565 drone images at 1.1 cm GSD, flown under campus authorization.

565
IMAGES, AIR AND GROUND
1.1 cm
GROUND SAMPLE DISTANCE
2.8 ha
MODELLED AREA

The 9th Street Historic Park, a block of restored 1870s–1900s houses on the Auraria Higher Education Center campus in downtown Denver, captured from the air and from the ground in one morning and reconstructed as a point cloud and textured mesh. Flown under a signed campus drone authorization.

Scope & deliverables.

Capture

Just over two hours on site, from 11:31 to 13:38 local, flown with a DJI Phantom 4 Pro (FC6310, 1-inch 20 MP RGB, 8.8 mm) on firmware v01.07.1641.

The model was built from 565 images, 548 of which calibrated. 462 were aerial frames at 45.7 m above takeoff – 54 nadir, the rest pitched about 80° down – with a further 147 low-level frames at a median 6 m, walking the facades, and 44 stills.

Georeferencing came from the on-board geotags, WGS 84 / UTM zone 13N with EGM96 heights; a GNSS base/rover session was run but not applied, for the reasons set out in the accuracy section. The flight ran under an Auraria campus drone request approved by AHEC Event Services, with a certificate of insurance and battery-safety documents on file and signage at the takeoff area. Conditions were daylight VFR with low wind and good visibility.

Deliverables

A textured 3D mesh exported in OBJ, PLY, FBX and DXF at 73–175 MB each, with a densified point cloud in PLY of about 447 MB and tie-point clouds in LAS. The Pix4D quality report records 1.13 cm GSD over 0.028 km² (2.8 ha) with 548 of 565 images calibrated.

A presentation deck and a printed banner were produced from the model. No orthomosaic or full DSM was exported; only the report’s DSM preview exists.

Cadence

One-off.

Method boundary

RGB photogrammetry georeferenced from the aircraft's geotags. The mesh and point cloud are internally consistent and suitable for visualisation, interpretive and presentation use, relative measurements of the buildings and grounds, and as a visual record of condition at the date flown. They are not suitable for as-built documentation to a stated tolerance, boundary or grading work, or any product carrying professional responsibility; that work is routed through a licensed Professional Land Surveyor.

How accuracy was held.

Produced to a documented RGB photogrammetry workflow.

High-overlap oblique coverage from two heights plus facade passes, with 96% of images calibrated and a mean reprojection error of 0.13 px – an internal block fit.

Ground control was attempted. One base point and seven rover points were logged with a 2.065 m pole, but every rover point resolved as FLOAT and the base as SINGLE. A trial project using three of the points showed the model disagreeing with the measured heights by about 6.7 m, so the control was discarded and the delivered model uses geotags only. There are no independent checkpoints. Produced to a documented RGB photogrammetry workflow; not tested to an ASPRS accuracy class.

The ASPRS ladder, explained→

Delivery commitments.

Standard-scope deliverables are typically available in the portal within 24 hours of flight; larger, survey-tested, or multisensor scopes receive quoted timeline.
Free reprocessing, revision, and re-delivery for the life of the project, within original scope.
Data is processed in the field and checked for completeness before demobilization (coverage, overlap, control residuals); final validation follows the stated delivery method.

Scope one like it.

15-minute reply. Fixed price. Lifetime data support.

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