SBGAT V2.05.1

New

• Uncertainty quantification in the surface polyhedron gravity model can now be computed from within SBGATGui

Improvements

• Users now must load one shape model in SBGATGui before being able to open up any of the analyses/observations windows.
• Removed deprecated AA functionalities

Bug fixes:

• SBGATMassPropertiesUQ's master script has been corrected with the proper SIM_PREFIX

SBGAT V2.04.1

SBGAT 2.04.1

New

• Introduced two new base classes, SBGATFilter and SBGATFilterUQ, the latter being tailored for uncertainty quantification in the considered geophysical properties
• A Python script producing shape "slices" has been added

Improvement

• SBGATMassPropertiesUQ now inherits from SBGATFilter
• SBGATPolyhedronGravityModelUQ now inherits from SBGATMassPropertiesUQ
• Clicking on a facet in SbgatGui now results in displaying the facet center coordinates.- Populated Examples folder with illustrative snippets for SBGATPolyhedronGravityModelUQ and SBGATMassPropertiesUQ. These tests should be run from a Python 3 process (run ../master_script.py) called from their build directory.

Regression

• As of April 7th 2019, OpenMP is no longer found by CMake on Mac.

SBGAT V2.02.4

New

• SBGAT 2.02.4 introduces SBGATPolyhedronGravityModelUQ, a class dedicated to uncertainty quantification in Polyhedron Gravity potentials and accelerations arising from a stochastic shape. This class enables the evaluation of the variance in the potential and covariance in the acceleration at any point in space (excluding shape edges)
• Expanded and consolidated the Tests suite.

Improvements

• Length unit consistency has been completely overhauled.
  • All of SBGAT's filters (SBGATMassproperties, SBGATSphericalHarmo, SBGATPolyhedronGravityModel,...) will return results using meters as length unit. For instance, calling GetAcceleration from the SBGATPolyhedronGravityModel class will always return an acceleration in m/s^2.
  • Similarly, any method from the aforementioned filters expects an input position to be expressed in meters.
  • Classes documentation has been updated to reflect this change
  • Overall consistency is enforced by manually specifying the unit in which a given shape model is specified through the use of SetScaleMeters or SetScaleKiloMeters. This way, a shape whose coordinates are expressed in kilometers can be connected to an instance of SBGATMassproperties or any other filter and used in a completely transparent manner as long as SetScaleKiloMeters is called on the filter before Update()
  • SBGATMassproperties, SBGATSphericalHarmo and SBGATPolyhedronGravityModel are initialized by default for a shape whose length unit are in meters (i.e the scaleFactor member is set to 1 by default, and set to 1000 if SetScaleKiloMeters() is called)
• Work is in progress to revamp the main page of the doxygen documentation

SBGAT V2.02.3

Bug fixes

• Fixed bug in SBGATSphericalHarmo that could have caused the evaluation of the spherical harmonics over a non-barycented shape to be incorrect.
• Pushed fix to latest version of SHARMLib dependency to address the same issue
• Modified CMakeLists.txt in Tests to fix issue caused by a conflicting header being sometimes included by one of VTK's dependencies

SBGAT 2.02.2

New

• Shape models can now be modified from within SBGATGui, by selecting a vertex and applying a Gaussian interpolation of the vertex displacement to a neighborhood of arbitrary choice.

Improvements

• Camera is now positioned at the correct distance from the targeted shape body upon loading
• Improved visual aspect of selected facet
• Improved visual aspect of loaded shapes

Bug fixes:

• Fixed bug in SBGATGui that prevented proper alignment of the shape model with its principal axes

SBGAT V2.02.1

New

• Second-moments about the mean in the volume, center-of-mass, unit-densiy inertia tensor, principal moments, principal dimensions and orientation of the principal axes can now be evaluated through the static methods of SBGATShapeUncertainty
• SBGATShapeUncertainty provides two methods to evaluate the statistical moments: a monte-carlo method ComputeInertiaStatisticsMC, and another method ComputeInertiaStatistics leveraging a linearized uncertainty model as proposed by Bercovici and McMahon (Inertia statistics of an uncertain small body shape, ICARUS 2019 (In Review). Both methods take the same argument (correleation length l and the standard deviation governing the error in the control point coordinates, directed along the average normal at these points). Both these methods assume that the shape error can be described as normally distributed and zero-mean.
• Added a new function in Tests to illustrate the convergence of the Monte-Carlo shape uncertainty sampling to the analytical prediction

Improvements

• SBGATMassProperties::SaveMassProperties is now saving the average radius (r_avg = cbrt(3/4 *Volume/pi)) to the JSON file
• SBGATMassproperties::GetPrincipalAxes could return 4 dcms, all representative of the same inertia ellipsoid. To enforce stability in the principal axes extractions, SBGATMassproperties::GetPrincipalAxes now returns the dcm that has the smallest-norm corresponding MRP.
• SBGAT will try to link against OpenMP by default. This behaviour can now be disabled by passing the --without-libomp flag to Homebrew or by passing the -DNO_OMP:BOOL=TRUE flag to CMake

Bug fixes:

• Fixed potential bug in SBGATPolyhedronGravityModel involving a parallel computing block where a variable with no viable reduction clause was being operated on
• SBGATMassproperties::GetPrincipalAxes is now returning the DCM [PB] converting from the body coordinate frame to the body principal frame. It was previously returning [BP]

SBGAT V2.01.2

SBGAT 2.01.2

New

• SBGATMassProperties now offers a method to save the computed mass properties to a JSON file (SBGATMassProperties::SaveMassProperties)
• A static method evaluating and saving the mass properties of the provided shape is now provided (SBGATMassProperties::ComputeAndSaveMassProperties)
• The Measures menu in SbgatGUI has been augmented with a Save geometric measures action

Improvements

• The inertia tensor normalization has changed. When computing the mass properties of a given small body, the following normalization is now applied to the inertia tensor: I_norm = I / (mass * r_avg ^ 2) where r_avg = cbrt(3/4 *Volume/pi). r_avg is now computed along with the other properties within SBGATMassProperties.
• The parallel axis theorem is no-longer applied to the small body. That is, the inertia will always be expressed about (0,0,0).
• Several GUI minors bug fixes

SBGAT V.2.01.1

New:

• Facets can now be individually selected in SbgatGui by clicking on them. If the surface PGM of the selected shape is available, the results for the selected facet will be shown in the console.

Improvements

• The Set Shape Mapper option was renamed to Set Results Overlay
• Several minor GUI bug fixes

Bug fixes:

• Fixed bug in SbgatCore that was due to an unnecessary rescaling of the computed potentials and accelerations within SbgatCore::ComputeSurfacePGM. This bug was manifesting itself when calling SbgatCore::ComputeSurfacePGM with a shape model whose coordinates were expressed in kilometers. This bug was not affecting SbgatGui since the latter automatically rescales input shapes to meters upon loading.

SBGAT 1.12.2

New:

• A previously evaluated surface Polyhedron Gravity Model can now be loaded from a JSON file via the static method SBGATPolyhedronGravityModel::LoadSurfacePGM
• SbgatGui can now overlay previously computed surface Polyhedron Gravity Model results over a corresponding shape model (aka featuring the same number of facets as the one used to generate the surface PGM)

Improvements

• The surface PGM now computes:
  • gravitational slopes
  • inertial gravity potentials
  • body-fixed gravity potentials
  • inertial gravity acceleration
  • body-fixed gravity acceleration

SBGAT V1.12.1

New:

• The gravity-gradient matrix deriving from the polyhedron gravity model can now be evaluated
• The evaluation of the surface polyhedron gravity model can now be saved to a JSON file through SBGATPolyhedronGravityModel::SaveSurfacePGM
• This static method is available in SbgatGUI as the evaluation of the PGM will now require the specification of an output file

Improvements

• Stronger typing of inputs in SBGATPolyhedronGravityModel
• SbgatGui will now ask users whethers a loaded shape should be barycentered/principal-axis aligned, and apply the corresponding transform if answered yes