ATCOR® and DROACOR® - Feature Comparison
Overview | Examples | Alternatives | Documentation | ATCOR-2/3 | ATCOR-4| DROACOR
The table below gives an overview of the features of the ATCOR and DROACOR packages as distributed through ReSe in comparison to current alternative codes, as available on the market:
|
Feature
|
DROACOR®
(ReSe)
|
ATCOR®-IDL
(ReSe)
|
ATCOR® Workflow
for Imagine (Geosystems)
|
ATCOR (Geomatica)
|
FLAASH (ENVI® /SSI)
|
|---|---|---|---|---|---|
| System Features | |||||
|
Supported Operating Systems
|
Windows, Linux, MacOSX
|
Windows, Linux, MacOSX
|
Windows
|
Windows, Linux
|
Windows, Linux
|
|
Base Software
|
none 1)
|
none 1)
|
Erdas Imagine
|
PCI Geomatica
|
ENVI
|
|
Radiative Transfer Code
|
LibRadtran
|
MODTRAN 5.4
|
MODTRAN 5.4
|
MODTRAN 5
|
MODTRAN 5
|
|
Satellite
|
no |
yes (A-23)
|
yes
|
yes
|
yes
|
|
Airborne
|
limited
|
yes (A-4)
|
no
|
no
|
yes
|
|
Drone
|
yes
|
limited
|
no
|
no
|
limited |
| Horizontal Scan | yes (V2) | no | no | no | no |
|
Hyperspectral
|
yes 3)
|
yes 3)
|
no
|
limited
|
yes
|
|
Ultraspectral (<2 nm) 2)
|
limited 3)
|
limited 3)
|
no
|
limited
|
yes
|
|
Extreme Tilt Angles 2)
|
yes |
no
|
no
|
no
|
yes
|
|
Batch Processing
|
yes (V2)
|
yes
|
yes
|
yes
|
no
|
|
Directory Processing
|
yes
|
no
|
yes |
no
|
no
|
| Correction Features | |||||
|
Terrain Correction
|
yes
|
yes
|
yes
|
yes
|
no
|
|
Variable Visibility
|
image mean |
yes
|
yes
|
yes
|
yes
|
|
Aerosol Type Detection
|
no
|
yes
|
yes
|
no
|
no
|
|
Adjacency Effect
|
yes
|
yes
|
yes
|
yes
|
yes
|
|
Water Vapor Retrieval
|
image mean |
yes 4)
|
yes
|
no
|
yes
|
|
Haze Removal
|
no
|
yes
|
yes
|
limited
|
no
|
|
Cirrus Cloud Removal
|
no
|
yes
|
yes
|
no
|
no
|
|
Cloud Shadow Removal
|
yes
|
yes
|
no
|
no
|
no
|
|
Preview of Spectra
|
no
|
yes
|
no
|
yes
|
no
|
|
Inflight Validation & Calibration
|
yes
|
yes
|
(one target)
|
no
|
no
|
|
Panel based calibration
|
yes
|
limited |
no
|
no
|
no
|
|
Normalize to Nadir View (Wide FOV)
|
no
|
yes
|
no
|
no
|
no
|
|
Physical Observer BRDF Correction
|
no |
yes
|
no
|
no
|
no
|
|
Spectral Polishing
|
yes |
yes
|
no
|
no
|
yes
|
|
Spectral Calibration
|
yes
|
yes
|
no
|
no
|
yes
|
| Adaptive Spectrum Correction |
yes
|
no
|
no
|
no
|
no
|
|
Spectral Smile Correction
|
no
|
yes
|
no
|
no
|
no
|
|
Empirical Line Correction
|
yes
|
yes
|
no
|
yes
|
yes (ENVI)
|
| Thermal Region Features | |||||
|
Surface Temperature
|
yes (V2)
|
yes
|
yes (Landsat7)
|
yes (Landsat7)
|
yes (ENVI)
|
|
Surface Emissivity
|
yes (V2)
|
yes
|
no
|
yes
|
yes (ENVI)
|
| Rugged Terrain Features | |||||
|
Terrain Height (DEM)
|
limited |
yes
|
yes
|
yes
|
no
|
|
DEM illumination Effects
|
yes
|
yes
|
yes
|
yes
|
no
|
|
Empirical BRDF Illumination Correction
|
yes |
yes
|
yes
|
no
|
no
|
Notes and Remarks:
1) ATCOR® and DROACOR® from ReSe run on the free IDL Virtual Machine.
2) Sensor-specific LUTs can be calculated in FLAASH directly through Modtran®, whereas DROACOR® LUTs are interpolated dynamically. This feature is particularly well suited for sensors at tilted angular conditions with large tilt angles. Also, 'ultraspectral' sensors having resolutions below 2nm are not ideally sampled in the ATCOR LUT. On the other hand, our experience has shown that 99% of all currently relevant data acquisitions are within the range which is covered by the ATCOR pre-calculated LUTs.
Note: The ATCOR LUTs are based on the accurate scaled DISORT (8 streams) multiple scattering option in atmospheric window regions and the accurate correlated-k algorithm in absorption regions. A variable spectral wavenumber resolution in MODTRAN is employed to achieve a constant wavelength resolution of 0.4 nm in the LUTs.
3) The IDL version of ATCOR supports the inclusion of new (user defined) sensors while DROACOR adapts dynamically to the sensor response. The resampling of the LUT allows interpolation of virtually any multispectral or hyperspectral sensor from the database (at 0.4 nm resolution). Inaccuracies due to this interpolation become relevant at spectral resolutions below 2 nm.
4) ATCOR uses the latest release of Modtran®5 (v5.4) and its LUTs are based on the HITRAN atlas of 2013 - a version which to our knowledge corrects earlier problems in the water vapor absorption bands. We will include any newer version of Modtran® as soon as it is available.
An independent comparison was published by Eyal Ben-Dor (2005) and indicates that the performance of ATCOR compares very well with other products available on the market, see: E. Ben-Dor, B. C. Kindel, and K. P. K1, "A comparison between six model-based methods to retrieve surface reflectance and water vapor content from hyperspectral data: A case study using synthetic AVIRIS data," presented at International Conference on Optics & Optoelectronics - ICOL 2005, Dehradun, India, 2005.
As ATCOR and DROACOR are continuously improved, we would be happy to participate in independent validation exercises and we would offer free time-limited licenses for such purposes.