Photogrammetry vs. regular stereogrammetry

Very popular with

drone photography

2

2

3

4

3

2..n

Beyer et al. 2018

Photogrammetry

expertize in Nantes (LPG)

sketchfab.com/LPG-3D

Le Mouélic et al. 2026

Halley's Comet

The Bayeux tapestry example

Le Mouélic et al. 2026

The Bayeux tapestry example

Does it work on

JANUS data?

YES!

First attempt in August 2024:

- just after the LEGA flyby

- use JPEG preview images

- uncalibrated data

- no camera model

- no geometric information

- mix of filters

Alignment success on 18 images

 👉 1st JANUS DTM!

21:24:30

21:24:01

…

How it works

Flight

path

Global alignment 👉 tie points

Images aligned

Tie points

Initial input:

- SPICE kernels location and expected attitude

- sensor size and expected focal length

- camera profile unconstrained

LRO basemap

36 images aligned:

- 14 PAN

- 3 R / G / B / V / CMT med / MT strong

- 2 NIR 1 & 2

👔 20k tie points identified

LRO basemap

⚙️ Mesh from dense points cloud

LRO basemap

📍 Ortho image

+ reference points to constrain the geographic coordinates on the Moon reference frame (ME)

LRO basemap

Output JANUS DTM

Comparison with Kaguya/LOLA

Kaguya resolution: 59 m/pix | 3-4 m accuracy

Longitude

profiles

1

2

3

Results

Results

Δh = -10 ± 220 m

(Janus pixel scale: 50m/pix)

Latitude

profiles

4

5

6

Results

Δh = -90 ± 150 m

(Janus pixel scale: 50m/pix)

Strengths 💪

Very low parallax requires

non-nadir looking

Not as accurate as

dedicated stereo pairs

Possible skew in GCO

due to rolling shutter

(can't be tested during the Cruise)

Opportunistic acquisitions

no additional DV

Single pass acquisition

Low impact on global coverage

Can be used with multi-filters

sequences (eg. R/G/B)

Fixed pointing

works on flyby ingress/egress or

limb to nadir looking slews

📣 Photogrammetry is not a replacement for stereo observations!

Weaknesses 🏋

EGA 2

To be tested over Madagascar and Africa.

EGA 1 - Cloud tops

No ground truth

Relevant for WG4 on Jupiter?

Other opportunities with NavCam (?)

LGA (2024) - not implemented

EGA 2 (2026) - not implemented

2024 - Not implemented by the SOC/MOC

2026 - Not implemented in favor of JANUS/MAJIS/NavCam synergy

2029 - Possible but major burst-mode limitations

Other opportunities with JMC

2024 - Yes! on the Moon

2026 - Planned for EGA2

2029 - TBC

x2

Global shape modeling