visual3d:documentation:modeling:landmarks:landmarks_overview
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visual3d:documentation:modeling:landmarks:landmarks_overview [2024/06/14 17:24] – created sgranger | visual3d:documentation:modeling:landmarks:landmarks_overview [2024/07/17 15:45] (current) – created sgranger | ||
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- | |===== Contents | + | ====== Landmarks Overview ====== |
**This page has been updated, but the original page can be found [[Visual3D: | **This page has been updated, but the original page can be found [[Visual3D: | ||
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Landmarks provide a powerful method of representing significant locations within space or locations defined by the model. Landmarks are created by either specifying a location in a segment coordinate system or by transforming markers or other landmarks into a significant location. | Landmarks provide a powerful method of representing significant locations within space or locations defined by the model. Landmarks are created by either specifying a location in a segment coordinate system or by transforming markers or other landmarks into a significant location. | ||
- | ====== Marker Set for Examples | + | ===== Marker Set for Examples ===== |
The following examples use the markers related to the left shank illustrated below. | The following examples use the markers related to the left shank illustrated below. | ||
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- LKJC: Left knee joint centre (landmark) | - LKJC: Left knee joint centre (landmark) | ||
- | [[File: | + | {{:Landmark_MarkerSet.png}} |
- | ====== General Options | + | ===== General Options ===== |
The landmark dialog can be broken into 3 sections: **** | The landmark dialog can be broken into 3 sections: **** | ||
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**** | **** | ||
- | ==== 1. Define Orientation Using ==== | + | === 1. Define Orientation Using === |
- | |Landmarks can be defined relative to a target, along a line, on a plane, or as a projection onto a line or a plane.\\ \\ Landmarks can be defined in lab space, or in a segment coordinate system. | + | |Landmarks can be defined relative to a target, along a line, on a plane, or as a projection onto a line or a plane.\\ \\ Landmarks can be defined in lab space, or in a segment coordinate system. |
- | ==== 2. Landmark Offset from Start Point (Reference) or Segment Origin | + | === 2. Landmark Offset from Start Point (Reference) or Segment Origin === |
Any time a landmark can be defined using Offsets in three directions, a user has the option to define the offsets manually (X/Y/Z or ML/ | Any time a landmark can be defined using Offsets in three directions, a user has the option to define the offsets manually (X/Y/Z or ML/ | ||
- | === 2a. Offset to Existing Calibration Target or Landmark | + | == 2a. Offset to Existing Calibration Target or Landmark == |
- | |The Offset to Existing Calibration Target or Landmark option allows users to get the location of a target (or landmark) relative to a plane or segment coordinate system. The offsets are populated automatically. This option can be used any time all three offsets can be specified, but it is only described as a special type for Type 4 since this is a crucial example. | + | |The Offset to Existing Calibration Target or Landmark option allows users to get the location of a target (or landmark) relative to a plane or segment coordinate system. The offsets are populated automatically. This option can be used any time all three offsets can be specified, but it is only described as a special type for Type 4 since this is a crucial example. |
- | === 2b. Offset Using the Following ML/AP/AXIAL Offsets | + | == 2b. Offset Using the Following ML/AP/AXIAL Offsets == |
- | |Offsets should be specified in meters unless " | + | |Offsets should be specified in meters unless " |
- | ==== 3. Calibration Only Landmark | + | === 3. Calibration Only Landmark === |
When a landmark is set to **" | When a landmark is set to **" | ||
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If a landmark is created in the associated motion files, it can be used to track a segment or for other calculations. | If a landmark is created in the associated motion files, it can be used to track a segment or for other calculations. | ||
- | ====== Landmark Types ====== | + | ===== Landmark Types ===== |
Although there are many different ways to define a landmark, all of these methods result in a " | Although there are many different ways to define a landmark, all of these methods result in a " | ||
- | ===== Type 1: In Reference Coordinate System | + | ==== Type 1: In Reference Coordinate System ==== |
|The simplest landmark is a landmark which is defined in a segment coordinate system. There are many variations of this, but a landmark can be defined in LAB space, a landmark can be defined in a segment coordinate system, or a landmark can be defined by a [[Visual3D: | |The simplest landmark is a landmark which is defined in a segment coordinate system. There are many variations of this, but a landmark can be defined in LAB space, a landmark can be defined in a segment coordinate system, or a landmark can be defined by a [[Visual3D: | ||
- | ==== Type 1a: In LAB Space ==== | + | === Type 1a: In LAB Space === |
- | |[[File: | + | |{{:Landmark_Type4_image.png}} |
\\ | \\ | ||
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**Sample Landmark Definition** (click to expand) | **Sample Landmark Definition** (click to expand) | ||
- | |**1. Create Relative_Axes: | + | |**1. Create Relative_Axes: |
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**Example Using Starting Point** (click to expand) | **Example Using Starting Point** (click to expand) | ||
- | |Landmarks can be created as an offset from the specified marker in a segment coordinate system or in the LAB coordinate system. **vRLK** that is created from **RLK** as an offset in the x direction in the LAB coordinate system. | + | |Landmarks can be created as an offset from the specified marker in a segment coordinate system or in the LAB coordinate system. **vRLK** that is created from **RLK** as an offset in the x direction in the LAB coordinate system. |
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- | ==== Type 1b: In a Segment Coordinate System | + | === Type 1b: In a Segment Coordinate System === |
- | |[[File: | + | |{{:Landmark_Type6_image.png}} |
\\ | \\ | ||
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**Sample Landmark Definition** (click to expand) | **Sample Landmark Definition** (click to expand) | ||
- | |**1. Create Relative_Segment: | + | |**1. Create Relative_Segment: |
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* [[|Bell and Brand Regression Equations]] | * [[|Bell and Brand Regression Equations]] | ||
* [[|Hip Landmark from Custom Regression Equation]] | * [[|Hip Landmark from Custom Regression Equation]] | ||
- | * A [[Knee_Alignment_Device|Knee Alignment Device]] (KAD) defines the joint centers by defining landmarks in the KAD segment coordinate system | + | * A [[Visual3D: |
* [[Visual3D: | * [[Visual3D: | ||
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- | ==== Type 1c: Relative to a 4x4 Rotation Matrix | + | === Type 1c: Relative to a 4x4 Rotation Matrix === |
**Sample Landmark Definition** (click to expand) | **Sample Landmark Definition** (click to expand) | ||
- | |**1. Create RTH_Origin: | + | |**1. Create RTH_Origin: |
- | ===== Type 2: On a Line ===== | + | ==== Type 2: On a Line ==== |
- | |[[File: | + | |{{:Landmark_Type1_image.png}} |
\\ | \\ | ||
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**Sample Landmark Definition** (click to expand) | **Sample Landmark Definition** (click to expand) | ||
- | |**1. Create Point_Line: | + | |**1. Create Point_Line: |
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**Create landmark as a midpoint** (click to expand) | **Create landmark as a midpoint** (click to expand) | ||
- | |The landmark **RKnee** is a point that is halfway between the lateral and medial knee markers **RLK** and **RMK**.\\ \\ The point on a line can be defined as a distance in percentage or distance in meters. When **Offset by Percent** is checked, the distance is defined as a percentage.\\ \\ **Note:** When using a Point on a Line landmark, only the AXIAL offset is used. | | + | |The landmark **RKnee** is a point that is halfway between the lateral and medial knee markers **RLK** and **RMK**.\\ \\ The point on a line can be defined as a distance in percentage or distance in meters. When **Offset by Percent** is checked, the distance is defined as a percentage.\\ \\ **Note:** When using a Point on a Line landmark, only the AXIAL offset is used. | {{:landmark_point_on_line.jpg}}| |
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- | ===== Type 3: On a Plane ===== | + | ==== Type 3: On a Plane ==== |
- | ==== Type 3a: On a Plane using manual offsets | + | === Type 3a: On a Plane using manual offsets === |
- | |[[File: | + | |{{:Landmark_Type2_image.png}} |
**Sample Landmark Definition** (click to expand) | **Sample Landmark Definition** (click to expand) | ||
- | |**1. Create LAND:**\\ \\ < | + | |**1. Create LAND:**\\ \\ < |
- | |A right handed orthogonal coordinate system is defined by the three points (P1, P2, P3).\\ \\ The origin of the coordinate system is at the point P1. The **frontal plane** of the coordinate system is defined by the three points. The positive AP direction is into the screen. | + | |A right handed orthogonal coordinate system is defined by the three points (P1, P2, P3).\\ \\ The origin of the coordinate system is at the point P1. The **frontal plane** of the coordinate system is defined by the three points. The positive AP direction is into the screen. |
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* [[Visual3D: | * [[Visual3D: | ||
* [[Visual3D: | * [[Visual3D: | ||
- | * [[Visual3D: | + | * [[Visual3D: |
- | ==== Type 3b: On a Plane using target/ | + | === Type 3b: On a Plane using target/ |
- | |[[File: | + | |{{:Landmark_Type7_image.png}} |
\\ | \\ | ||
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**Landmark Definition** (click to expand) | **Landmark Definition** (click to expand) | ||
- | |**1. Create Relative_Tracking: | + | |**1. Create Relative_Tracking: |
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**Example 1** (click to expand) | **Example 1** (click to expand) | ||
- | |To define a landmark as a point on a plane defined by 3 points\\ \\ * Select the Targets and/or Landmarks radio button\\ * Select three targets and/or landmarks for the Reference/ | + | |To define a landmark as a point on a plane defined by 3 points\\ \\ * Select the Targets and/or Landmarks radio button\\ * Select three targets and/or landmarks for the Reference/ |
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* [[Visual3D: | * [[Visual3D: | ||
- | ===== Type 4: Project on a Line ===== | + | ==== Type 4: Project on a Line ==== |
A target or landmark may be projected onto a line defined by two points.\\ | A target or landmark may be projected onto a line defined by two points.\\ | ||
- | [[File: | + | {{:Landmark_Type3_image.png}} {{:Landmark_Type3_image_AltView.png}}\\ |
**Landmark Definition** (click to expand) | **Landmark Definition** (click to expand) | ||
- | |**1. Create Project_Line: | + | |**1. Create Project_Line: |
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**Project the heel target onto the line defined by the mediolateral ankle targets** (click to expand) | **Project the heel target onto the line defined by the mediolateral ankle targets** (click to expand) | ||
- | |Point projection onto a line can be used at the shoulder to project a lateral target on to a vertical line passing through the acromium or it can be used at the knee to project lateral or medial targets on a functional axis.\\ \\ The **RAnkleCenter** is the point that is created by projecting the **RHL** heel marker onto the line created from the lateral and medial ankle markers **RLA** and **RMA**. | + | |Point projection onto a line can be used at the shoulder to project a lateral target on to a vertical line passing through the acromium or it can be used at the knee to project lateral or medial targets on a functional axis.\\ \\ The **RAnkleCenter** is the point that is created by projecting the **RHL** heel marker onto the line created from the lateral and medial ankle markers **RLA** and **RMA**. |
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* [[Visual3D: | * [[Visual3D: | ||
- | ===== Type 5: Project on a Plane ===== | + | ==== Type 5: Project on a Plane ==== |
A point can be projected onto a plane defined by three points.\\ | A point can be projected onto a plane defined by three points.\\ | ||
- | [[File: | + | {{:Landmark_Type5_image.png}} {{:Landmark_Type5_image_AltView.png}}\\ |
**Landmark Definition** (click to expand) | **Landmark Definition** (click to expand) | ||
- | |**1. Create Project_Plane: | + | |**1. Create Project_Plane: |
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**Example: Project the iliac crest target onto the plane defined by the R/LASIS and RPSIS** (click to expand) | **Example: Project the iliac crest target onto the plane defined by the R/LASIS and RPSIS** (click to expand) | ||
- | |By projecting multiple landmarks onto the same plane you can build segment coordinates systems in a specific plane.\\ \\ The **RPPinPlane** is the point that is created by projecting the **RPP** marker on the illiac crest onto the plane created from the right and left ASIS's (**RASI**, | + | |By projecting multiple landmarks onto the same plane you can build segment coordinates systems in a specific plane.\\ \\ The **RPPinPlane** is the point that is created by projecting the **RPP** marker on the illiac crest onto the plane created from the right and left ASIS's (**RASI**, |
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- | ===== Digitized Landmarks | + | ==== Digitized Landmarks ==== |
Digitized landmarks are defined using a digitized pointer and again result in a " | Digitized landmarks are defined using a digitized pointer and again result in a " | ||
- | ===== Functional Landmarks | + | ==== Functional Landmarks ==== |
Functional landmarks indicate the locations of functional joints. Calculating functional joint positions requires movement of one segment relative to another segment. The chosen algorithm then searches for a point (or for a one degree of freedom joint, an axis) that is stationary relative to the 2 segments (or 2 sets of markers). | Functional landmarks indicate the locations of functional joints. Calculating functional joint positions requires movement of one segment relative to another segment. The chosen algorithm then searches for a point (or for a one degree of freedom joint, an axis) that is stationary relative to the 2 segments (or 2 sets of markers). | ||
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See the in-depth explanation of [[Visual3D: | See the in-depth explanation of [[Visual3D: | ||
- | |||
- | Retrieved from "" | ||
visual3d/documentation/modeling/landmarks/landmarks_overview.1718385849.txt.gz · Last modified: 2024/06/14 17:24 by sgranger