Oblique GSD and footprint
For a camera tilted off straight down, the ground each pixel covers at the image center and its near and far edges, the trapezoid the image covers, and a warning when the view reaches the horizon.
Planning and education aid. Not for primary navigation. Full disclaimer
Experimental: not yet fully verified. How results are checked
At the center each pixel covers 3.88 cm across and 5.48 cm along the view, against 2.74 cm straight down; the whole image is on the ground.
| Corner | Ahead | Right |
|---|---|---|
| near left | 33.33 m | -70.71 m |
| near right | 33.33 m | 70.71 m |
| far right | 300.00 m | 212.13 m |
| far left | 300.00 m | -212.13 m |
- GSD at the center, along
- GSD at the near edge
- GSD at the far edge
- GSD straight down
- Near edge ahead
- Far edge ahead
Provenance
- Computed by
- drone.photogrammetry.oblique-gsd 1.0.0, core 0.1.0
- Model
- Pinhole camera pitched θ from nadir over flat ground: each sensor point's ray, f·a + y·u + x·r with a the optical axis, meets the ground at height H; GSD is the ground span of one pixel step there, along and across (Wolf, Dewitt & Wilkinson 2014, ch. 10)
- Accuracy
- Exact for a pinhole camera over flat ground; lens distortion and terrain change it
- Notes
- 1 shown with the answer
- Cites
- Wolf, P. R., Dewitt, B. A., and Wilkinson, B. E., McGraw-Hill, Elements of Photogrammetry with Applications in GIS
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: Pinhole camera pitched θ from nadir over flat ground: each sensor point's ray, f·a + y·u + x·r with a the optical axis, meets the ground at height H; GSD is the ground span of one pixel step there, along and across (Wolf, Dewitt & Wilkinson 2014, ch. 10)
Accuracy: Exact for a pinhole camera over flat ground; lens distortion and terrain change it
Worked example: Tilted 45° at 100 m with a 1-inch, 8.8 mm camera. Source: add-drone-suite 45° oblique scenario. It is golden test vector v012, and every build checks the tool still gives its answer within its tolerance.
You enter
- Focal length
- 8.8 mm
- Height above ground
- 100 m
- Image height
- 3648
- Image width
- 5472
- Tilt from straight down
- 45 deg
- Sensor width
- 13.2 mm
You get
- GSD at the center, across
- 3.88 cm
- GSD at the center, along
- 5.48 cm
- GSD at the near edge
- 2.44 cm
- GSD at the far edge
- 21.92 cm
- GSD straight down
- 2.74 cm
- Near edge ahead
- 33.33 m
- Far edge ahead
- 300 m
- Horizon
- the whole image is on the ground
Review: Not yet independently reviewed by a Part 107 remote pilot.
Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 14 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Elements of Photogrammetry with Applications in GIS, Wolf, P. R., Dewitt, B. A., and Wilkinson, B. E., McGraw-Hill, 4th edition. Chapter 10 (tilted and oblique photographs). Read free.
Terms
- GSD: ground sampling distance
- The ground width one image pixel covers, such as 2 cm per pixel. A smaller GSD shows more detail. Source: Elements of Photogrammetry with Applications in GIS
Experimental means this tool has not yet met the stable bar: at least 20 golden vectors, differential tests, and an independent worked example.