photic - A Physics-Based, Satellite-Derived Bathymetry Model

About

photic is a C implementation of the physics-based, satellite-derived bathymetry model as described in (Blake, 2020).

Model

photic is a semi-analytical model for bathymetry, water turbidity and bottom composition; which is primarily based on the physics-based model, HOPE, of (Lee, 1998)(Lee, 1999). Unlike the model of Lee, which was originally designed to use hyperspectral imagery, our model is specifically designed to use multispectral satellite imagery. In particular, we adapt to the greatly decreased spectral resolution by introducing temporal and spatial assumptions on the depth and water turbidity.

The model is described in detail here.

Features

Open Data from photic

DISCLAIMER! This should be obvious, but these data from photic should not be used for navigation or for any other purpose relating to safety at sea or where commercial losses could occur.

Each of these studies used multiple LANDSAT 8 images.

Western Australia - Pilbara Coast from Exmouth to Whim Creek

The modelled satellite-derived bathymetry comprised $17060$ $\text{km}^2$ at a horizontal resolution of 30m. The modelled gridded dataset has dimensions 12662 by 16077 and is projected in the WGS84 (EPSG:4326) coordinate system. The dataset is a 60 MB compressed geotiff, which can be downloaded here.

Western Australia - Exmouth Gulf

The modelled satellite-derived bathymetry comprised $4175$ $\text{km}^2$ at a horizontal resolution of 30m. The modelled gridded dataset has dimensions 3930 by 2858 and is projected in the WGS84 (EPSG:4326) coordinate system. The dataset is a 14 MB compressed geotiff, which can be downloaded here.

Western Australia - Murion Island

The modelled satellite-derived bathymetry comprised $257$ $\text{km}^2$ at a horizontal resolution of 30m. The modelled gridded dataset has dimensions 1040 by 305 and is projected in the WGS84 (EPSG:4326) coordinate system. The dataset is a 675 KB compressed geotiff, which can be downloaded here. (The image below has been rotated 90 degrees.)

UAE - Abu Dhabi to Dubai

The modelled satellite-derived bathymetry comprised $3138$ $\text{km}^2$ at a horizontal resolution of 30m. The modelled gridded dataset has dimensions 3370 by 4700 and is projected in the WGS84 (EPSG:4326) coordinate system. The dataset is a 11.5 MB compressed geotiff, which can be downloaded here.

UAE - Mubarraz Island to Abu Dhabi

The modelled satellite-derived bathymetry comprised $11408$ $\text{km}^2$ at a horizontal resolution of 30m. The modelled gridded dataset has dimensions 4535 by 7476 and is projected in the WGS84 (EPSG:4326) coordinate system. The dataset is a 38 MB compressed geotiff, which can be downloaded here.

Qatar - Eastern Qatar to Sir Baniyas Island

The modelled satellite-derived bathymetry comprised $14716$ $\text{km}^2$ at a horizontal resolution of 30m. The modelled gridded dataset has dimensions 5774 by 6905 and is projected in the WGS84 (EPSG:4326) coordinate system. The dataset is a 47 MB compressed geotiff, which can be downloaded here.

Qatar, Bahrain and Saudi Arabia

The modelled satellite-derived bathymetry comprised $12232$ $\text{km}^2$ at a horizontal resolution of 30m. The modelled gridded dataset has dimensions 7361 by 7344 and is projected in the WGS84 (EPSG:4326) coordinate system. The dataset is a 43 MB compressed geotiff, which can be downloaded here.

Installation & Dependencies

NetCDF

NetCDF developer libraries can be installed via brew with brew install netcdf.

OpenMP

The semi-analytical model at the core of photic uses OpenMP for parallelisation, and can be installed via brew with brew install libomp.

PGPLOT

PGPLOT can be installed (on a mac) via macports with port install pgplot, or compiled from source, which can be downloaded from

https://sites.astro.caltech.edu/~tjp/pgplot/

Giza

Alternatively, Giza can be used as a drop-in replacement for the ageing PGPLOT library:

https://github.com/danieljprice/giza

Linenoise

photic uses the linenoise library for the repl:

https://github.com/antirez/linenoise

XQuartz (OSX)

For interactive graphics (on a mac) we need to install XQuartz:

https://www.xquartz.org/

GDAL

Converting from LANDSAT and Sentinel-2 imagery into a photic-readable gridded file requires gdal (https://gdal.org/), which can be installed via brew with brew install gdal.

ACOLITE

All experiments with photic have used the excellent atmospheric correction software, ACOLITE (https://odnature.naturalsciences.be/remsem/software-and-data/acolite):

https://github.com/acolite/acolite

References

(Blake, 2020) https://arxiv.org/abs/2002.02298

(Lee, 1998) Z. Lee et al, ``Hyperspectral remote sensing for shallow waters. I. A semianalytical model'', \textit{Applied Optics}, vol. 37, no. 27, pp. 6329-6338, 1998

(Lee, 1999) Z. Lee et al, ``Hyperspectral remote sensing for shallow waters: 2. Deriving bottom depths and water properties by optimization'', \textit{Applied Optics}, vol. 38, no. 18, pp. 3831-3843, 1999