Compass (plugin) - Revision history

Daniel at 15:12, 24 July 2024

2024-07-24T15:12:38Z

← Older revision		Revision as of 17:12, 24 July 2024
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	A detailed description of the SNE algorithm is currently being prepared (Nov 2018). A preprint version can be found here: https://www.researchgate.net/publication/329529172_Extraction_of_high-resolution_structural_orientations_from_digital_data_A_Bayesian_approach		A detailed description of the SNE algorithm is currently being prepared (Nov 2018). A preprint version can be found here: https://www.researchgate.net/publication/329529172_Extraction_of_high-resolution_structural_orientations_from_digital_data_A_Bayesian_approach

			= About the author =
	= ~~The~~ author =

	Sam Thiele (see his website: [https://www.samthiele.science https://www.samthiele.science])		Sam Thiele (see his website: [https://www.samthiele.science https://www.samthiele.science])

Daniel at 15:12, 24 July 2024

2024-07-24T15:12:09Z

← Older revision		Revision as of 17:12, 24 July 2024
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	A detailed description of the SNE algorithm is currently being prepared (Nov 2018). A preprint version can be found here: https://www.researchgate.net/publication/329529172_Extraction_of_high-resolution_structural_orientations_from_digital_data_A_Bayesian_approach		A detailed description of the SNE algorithm is currently being prepared (Nov 2018). A preprint version can be found here: https://www.researchgate.net/publication/329529172_Extraction_of_high-resolution_structural_orientations_from_digital_data_A_Bayesian_approach


			= The author =

			Sam Thiele (see his website: [https://www.samthiele.science https://www.samthiele.science])

Sam: /* Further reading and citation */

2018-12-13T04:59:29Z

Sam: /* Trace tool: Digitise and measure traces and contacts */

2018-12-12T22:05:06Z

Trace tool: Digitise and measure traces and contacts

← Older revision		Revision as of 00:05, 13 December 2018
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	The results of this tool depend on the cost function used by the least-cost path algorithm. A variety of these have been implemented, and can be activated by clicking the ''algorithm dropdown'' (settings icon). The different cost functions that have been implemented are:		The results of this tool depend on the cost function used by the least-cost path algorithm. A variety of these have been implemented, and can be activated by clicking the ''algorithm dropdown'' (settings icon). The different cost functions that have been implemented are:
	*Darkness [default] - traces follow dark points in the cloud. This is good for fracture traces defined by shadow.		*''Darkness [default]'' - traces follow dark points in the cloud. This is '''good for fracture traces defined by shadow'''.
	*Lightness - traces follow light points in the cloud. This is good for light-coloured structures such as veins.		*''Lightness'' - traces follow light points in the cloud. This is '''good for light-coloured structures such as veins'''.
	*RGB - traces avoid colour contrasts, following points with a similar colour to the start and end points.		*''RGB'' - traces avoid colour contrasts, following points with a similar colour to the start and end points.
	*Curvature - traces follow points on ridges and valleys. This can be good for fracture traces with high relief but can be slow and sensitive to noise. ~~For better performance, use the~~ ''~~[[Curvature]]'' and ''[[Scalar fields\Gaussian filter]]'' tools to create a scalar field which highlights areas of high curvature, then use the~~ ''~~Inverse Scalar Field'' cost function.~~		*''Curvature'' - traces follow points on ridges and valleys. This can be good for fracture traces with high relief but can be slow and sensitive to noise.
	*Gradient - traces follow colour boundaries ~~such as lithological contacts. Note that this can be slow and is very sensitive to noise~~. ~~For better performance, use the ''[[Scalar fields\Gradient]]~~'' ~~tool and~~ ''~~Inverse Scalar Field~~'' ~~cost function as described above~~.		*''Gradient'' - traces follow colour boundaries. '''Excellent for tracing contacts between lithologies''' with different colour.
	*Distance - traces take the shortest path. I'm not sure what this is good for.		*''Distance'' - traces take the shortest path. I'm not sure what this is good for.
	*Scalar Field - traces follow low values in the active (displayed) scalar field. Use this to implement custom cost functions.		*''Scalar Field'' - traces follow low values in the active (displayed) scalar field. Use this to implement custom cost functions.
	*Inverse Scalar Field - traces follow high values in the active (displayed) scalar field. Use this to implement custom cost functions.		*''Inverse Scalar Field'' - traces follow high values in the active (displayed) scalar field. Use this to implement custom cost functions.

	When using this tool it is important to note that its performance (i.e. speed) scales with trace length. Hence, it can be used with large point clouds if trace lengths are kept small (though long traces can be quickly digitised as multiple segments). Asking the tool to find long traces may result in system crashes.		When using this tool it is important to note that its performance (i.e. speed) scales with trace length. Hence, it can be used with large point clouds if trace lengths are kept small (though long traces can be quickly digitised as multiple segments). Asking the tool to find long traces may result in system crashes.

Sam: /* Trace tool: Digitise and measure traces and contacts */

2018-12-12T22:01:59Z

Trace tool: Digitise and measure traces and contacts

← Older revision		Revision as of 00:01, 13 December 2018
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	[[File: ccCompass_method.png\|\|frame\|center\|Schematic showing the least-cost path approach to trace detection in a point cloud implemented in the Compass plugin.]]		[[File: ccCompass_method.png\|\|frame\|center\|Schematic showing the least-cost path approach to trace detection in a point cloud implemented in the Compass plugin.]]

	The results of this tool depend on the cost function used by the least-cost path algorithm. A variety of these have been implemented, and can be activated by clicking the ''algorithm dropdown'' (settings icon)~~. Note that cost functions can be used simultaneously~~. The different cost functions that have been implemented are:		The results of this tool depend on the cost function used by the least-cost path algorithm. A variety of these have been implemented, and can be activated by clicking the ''algorithm dropdown'' (settings icon). The different cost functions that have been implemented are:
	*Darkness [default] - traces follow dark points in the cloud. This is good for fracture traces defined by shadow.		*Darkness [default] - traces follow dark points in the cloud. This is good for fracture traces defined by shadow.
	*Lightness - traces follow light points in the cloud. This is good for light-coloured structures such as veins.		*Lightness - traces follow light points in the cloud. This is good for light-coloured structures such as veins.
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	Automatic plane fitting can be enabled/disabled (it is disabled by default) in the ''algorithm'' menu (settings icon) or holding the shift key when accepting the trace. Plane orientations are expressed using the dip/dip direction convention.		Automatic plane fitting can be enabled/disabled (it is disabled by default) in the ''algorithm'' menu (settings icon) or holding the shift key when accepting the trace. Plane orientations are expressed using the dip/dip direction convention.


	== Lineation tool: Measure lineations ==		== Lineation tool: Measure lineations ==

Sam: /* Estimate structure normals */

2018-11-30T05:38:21Z

Estimate structure normals

← Older revision		Revision as of 07:38, 30 November 2018
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	== Estimate structure normals ==		== Estimate structure normals ==

	Uses a bayesian plane-fitting method and moving window search algorithm to identify optimum best-fit planes for each point along the selected structure trace and hence estimate structure normals. If one (or more) GeoObjects are selected SNEs will be created for all traces within each object. If objects have upper and lower surfaces defined then true-thicknesses corresponding to each orientation can also be estimated. Results are stored on a "SNE" point cloud, including thickness, dip and dip direction scalar fields. Details of the different options that can be used for this tool are shown in the figure below.		Uses a bayesian plane-fitting method and moving window search algorithm to identify optimum best-fit planes for each point along the selected structure trace and hence estimate structure normals. If one (or more) GeoObjects are selected SNEs will be created for all traces within each object. If objects have upper and lower surfaces defined then true-thicknesses corresponding to each orientation can also be estimated. Results are stored on a "SNE" point cloud, including thickness, dip and dip direction scalar fields. Details of the different options that can be used for this tool are shown in the figure below. Note that fit-planes are not allowed to include pinch-nodes, meaning these can be used to separate different sections of a structure (e.g. a segmented dyke).

	[[File:sne_gui.png ‎\|frame\|center\|Screenshot of the SNE estimation dialog and associated explanation of each option.]]		[[File:sne_gui.png ‎\|frame\|center\|Screenshot of the SNE estimation dialog and associated explanation of each option.]]

	~~Note that fit-planes are not allowed~~ to ~~include pinch-nodes, meaning these can be used to separate different sections of a structure (e.g. a segmented dyke). Also note that~~ the results ~~of this algorithm should be vetted carefully~~, as geometric quirks will often lead to wildly inaccurate results. The "segment" tool (scissors) can be used to delete unwanted SNEs as with any other point cloud. SNEs are also compatible with the stereonet tool in the qFacets plugin, which can aid in filtering erroneous results.		'''When using this algorithm it is critical to carefully filter the results, as geometric quirks will often lead to wildly inaccurate results'''. The "segment" tool (scissors) can be used to delete unwanted SNEs as with any other point cloud. SNEs are also compatible with the stereonet tool in the qFacets plugin, which can aid in filtering erroneous results.

	== Export SVG ==		== Export SVG ==

Sam: /* Estimate structure normals */

2018-11-20T11:08:15Z

Estimate structure normals

← Older revision		Revision as of 13:08, 20 November 2018
Line 77:		Line 77:
	Uses a bayesian plane-fitting method and moving window search algorithm to identify optimum best-fit planes for each point along the selected structure trace and hence estimate structure normals. If one (or more) GeoObjects are selected SNEs will be created for all traces within each object. If objects have upper and lower surfaces defined then true-thicknesses corresponding to each orientation can also be estimated. Results are stored on a "SNE" point cloud, including thickness, dip and dip direction scalar fields. Details of the different options that can be used for this tool are shown in the figure below.		Uses a bayesian plane-fitting method and moving window search algorithm to identify optimum best-fit planes for each point along the selected structure trace and hence estimate structure normals. If one (or more) GeoObjects are selected SNEs will be created for all traces within each object. If objects have upper and lower surfaces defined then true-thicknesses corresponding to each orientation can also be estimated. Results are stored on a "SNE" point cloud, including thickness, dip and dip direction scalar fields. Details of the different options that can be used for this tool are shown in the figure below.

	[[File:sne_gui.png ‎\|frame\|center\|SNE estimation dialog ~~explaining~~ each ~~of the available options~~.]]		[[File:sne_gui.png ‎\|frame\|center\|Screenshot of the SNE estimation dialog and associated explanation of each option.]]

	Note that fit-planes are not allowed to include pinch-nodes, meaning these can be used to separate different sections of a structure (e.g. a segmented dyke). Also note that the results of this algorithm should be vetted carefully, as geometric quirks will often lead to wildly inaccurate results. The "segment" tool (scissors) can be used to delete unwanted SNEs as with any other point cloud. SNEs are also compatible with the stereonet tool in the qFacets plugin, which can aid in filtering erroneous results.		Note that fit-planes are not allowed to include pinch-nodes, meaning these can be used to separate different sections of a structure (e.g. a segmented dyke). Also note that the results of this algorithm should be vetted carefully, as geometric quirks will often lead to wildly inaccurate results. The "segment" tool (scissors) can be used to delete unwanted SNEs as with any other point cloud. SNEs are also compatible with the stereonet tool in the qFacets plugin, which can aid in filtering erroneous results.

Sam: /* Estimate structure normals */

2018-11-20T11:07:16Z

Estimate structure normals

← Older revision		Revision as of 13:07, 20 November 2018
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	[[File:sne_gui.png ‎\|frame\|center\|SNE estimation dialog explaining each of the available options.]]		[[File:sne_gui.png ‎\|frame\|center\|SNE estimation dialog explaining each of the available options.]]

	Note that fit-planes are not allowed to include pinch-nodes, meaning these can be used to separate different sections of a structure (e.g. a segmented dyke). Also note that the results of this algorithm should be vetted carefully, as geometric quirks will often lead to wildly inaccurate results. The "segment" tool (scissors) can be used to delete unwanted SNEs as with any other point cloud. SNEs are also compatible with the stereonet tool in the qFacets plugin, which can aid in filtering erroneous results.		Note that fit-planes are not allowed to include pinch-nodes, meaning these can be used to separate different sections of a structure (e.g. a segmented dyke). Also note that the results of this algorithm should be vetted carefully, as geometric quirks will often lead to wildly inaccurate results. The "segment" tool (scissors) can be used to delete unwanted SNEs as with any other point cloud. SNEs are also compatible with the stereonet tool in the qFacets plugin, which can aid in filtering erroneous results.


	== Export SVG ==		== Export SVG ==

Sam: /* Further reading and citation */

2018-11-20T11:05:53Z

Sam: /* Further reading and citation */

2018-11-20T11:04:43Z

← Older revision		Revision as of 06:59, 13 December 2018
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	[2] ''Thiele, ST., Micklethwaite, S., Bourke, P., Verrall, M., Kovesi, P., 2015, Insights into the mechanics of en-échelon sigmoidal vein formation using ultra-high resolution photogrammetry and computed tomography, Journal of Structural Geology, Volume 77, Pages 27-44, ISSN 0191-8141, http://dx.doi.org/10.1016/j.jsg.2015.05.006.''		[2] ''Thiele, ST., Micklethwaite, S., Bourke, P., Verrall, M., Kovesi, P., 2015, Insights into the mechanics of en-échelon sigmoidal vein formation using ultra-high resolution photogrammetry and computed tomography, Journal of Structural Geology, Volume 77, Pages 27-44, ISSN 0191-8141, http://dx.doi.org/10.1016/j.jsg.2015.05.006.''

	A detailed description of the SNE algorithm is currently being prepared (Nov 2018).		A detailed description of the SNE algorithm is currently being prepared (Nov 2018). A preprint version can be found here: https://www.researchgate.net/publication/329529172_Extraction_of_high-resolution_structural_orientations_from_digital_data_A_Bayesian_approach

← Older revision		Revision as of 13:05, 20 November 2018
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	If you found this tool useful, please cite ''Thiele et al., 2017''. The publication also contains a more detailed description of the methods employed by this plugin.		If you found this tool useful, please cite ''Thiele et al., 2017''. The publication also contains a more detailed description of the methods employed by this plugin.

	[1] ''Thiele, S. T., Grose, L., Samsu, A., Micklethwaite, S., Vollgger, S. A., and Cruden, A. R.: Rapid, semi-automatic fracture and contact mapping for point clouds, images and geophysical data, Solid Earth ~~Discuss.~~, https://doi.org/10.5194/se-2017~~-83, in review~~, 2017''		[1] ''Thiele, S. T., Grose, L., Samsu, A., Micklethwaite, S., Vollgger, S. A., and Cruden, A. R.: Rapid, semi-automatic fracture and contact mapping for point clouds, images and geophysical data, Solid Earth, https://doi.org/10.5194/se-8-1241-2017, 2017''

	Further information on the automatic vetting process for structural orientation estimates can be found in:		Further information on the automatic vetting process for structural orientation estimates can be found in:

← Older revision		Revision as of 13:04, 20 November 2018
Line 94:		Line 94:
	If you found this tool useful, please cite ''Thiele et al., 2017''. The publication also contains a more detailed description of the methods employed by this plugin.		If you found this tool useful, please cite ''Thiele et al., 2017''. The publication also contains a more detailed description of the methods employed by this plugin.

	''Thiele, S. T., Grose, L., Samsu, A., Micklethwaite, S., Vollgger, S. A., and Cruden, A. R.: Rapid, semi-automatic fracture and contact mapping for point clouds, images and geophysical data, Solid Earth Discuss., https://doi.org/10.5194/se-2017-83, in review, 2017''		[1] ''Thiele, S. T., Grose, L., Samsu, A., Micklethwaite, S., Vollgger, S. A., and Cruden, A. R.: Rapid, semi-automatic fracture and contact mapping for point clouds, images and geophysical data, Solid Earth Discuss., https://doi.org/10.5194/se-2017-83, in review, 2017''

	Further information on the automatic vetting process for structural orientation estimates can be found in:		Further information on the automatic vetting process for structural orientation estimates can be found in:

	[1] ''Thiele, ST., Micklethwaite, S., Bourke, P., Verrall, M., Kovesi, P., 2015, Insights into the mechanics of en-échelon sigmoidal vein formation using ultra-high resolution photogrammetry and computed tomography, Journal of Structural Geology, Volume 77, Pages 27-44, ISSN 0191-8141, http://dx.doi.org/10.1016/j.jsg.2015.05.006.''		[2] ''Thiele, ST., Micklethwaite, S., Bourke, P., Verrall, M., Kovesi, P., 2015, Insights into the mechanics of en-échelon sigmoidal vein formation using ultra-high resolution photogrammetry and computed tomography, Journal of Structural Geology, Volume 77, Pages 27-44, ISSN 0191-8141, http://dx.doi.org/10.1016/j.jsg.2015.05.006.''

	A detailed description of the SNE algorithm is currently being prepared (Nov 2018).		A detailed description of the SNE algorithm is currently being prepared (Nov 2018).