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SEDRIS Spatial Reference Model
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2
SRM Tutorial
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3
Outline
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4
Section I
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5
In the Beginning ...
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6
Simulation Interfaces
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7
A Spectrum of Constructive, Live and Virtual
Capabilities Support Training, Planning & Analysis
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8
A Spectrum of Constructive, Live and Virtual
Capabilities Support Training, Planning & Analysis
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9
The Interface Canyons
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10
Why is a Spatial Reference Model (SRM) Needed?
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11
SRM Requirements
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12
Location is Not Enough
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13
A Shared Solution is Required!
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14
Section II
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15
It’s a Loooong Way Up
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16
Here’s an Interesting Perspective
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17
Not All Projections are Geodetic!
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18
More Familiar?
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19
Spatial, the Final Frontier
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20
Coordinates
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21
DRM <Location> (Page 15)
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22
Spatial Reference Frames
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23
SRF Example
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24
Named SRFs in SEDRIS
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25
Named SRFs in SEDRIS
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26
Coordinates & Coordinate Systems
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27
ERMs
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28
Standard Ellipsoids
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29
Standard Spheres
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30
Standard Horizontal Datums
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31
Standard Vertical Datums
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32
ORMs
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33
Many SRFs
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34
Spatial Reference Model
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35
Operations on Coordinates
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36
Types of Operation Errors
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37
Section IIB
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38
Ellipsoidal Earth Reference Model (ERM) Geometry
& Notation
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39
Latitude, Longitude and Height for Ellipsoids
& Spheres
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40
Cross-Section of the Geoid, Ellipsoid and Earth
Surface
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41
Gravitational Field and the Geoid, Ellipsoid
& Earth Surface
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42
SRM Refresher
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43
Section III
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44
Development of Surfaces to Generate Maps
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45
Map Projections
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46
Projecting from 2D to 1D
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47
Cylindrical Projections
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48
Planar Projections
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49
A Stereographic Projection
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50
Conic Projections
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51
Mercator Projection
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52
Oblique Mercator Projection*
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53
Transverse Mercator Map of the Western Hemisphere*
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54
Universal Transverse Mercator (60)
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55
Lines of Constant Heading*
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56
Great Circle Arc between Moscow and Washington
D.C.*
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57
Many Map Projections are Conformal
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58
Section IV
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59
Augmented Projection-Based SRFs
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60
“3D” Projection-based SRFs
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61
Coordinate Operations affect Geometrical Relationships
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62
SRF Operation Relationships
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63
Geometric Distortions
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64
Distance and Elevation Angle
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65
Distance Distortion Can Be Mitigated, Somewhat
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66
Azimuth
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67
How Much Azimuth Distortion?
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68
Flattening the ERM: Distance and Geometry
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69
Section V
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70
Modelers Often Prefer Cartesian Coordinate
Frameworks
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71
Non-real World 3-D Systems are often Used.
Why ?
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72
Relationships Between Coordinate Systems and
Simulations
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73
MCG&I and Dynamics Modeling
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74
MCG&I
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75
Dynamics Modeling
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76
Section VI
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77
Euclidean Distance in a Rectangular Framework
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78
Defining Geometrical Concepts
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79
The Traditional Surveying Process
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80
Surveying is a Complex Process
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81
Traditional Distance Determination in Surveys
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82
Surveying on a Flat ERM
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83
Surveying on a Flat ERM with a Terrain Model
Added
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84
Surveying on a Spherical ERM
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85
Chaining on a Spherical ERM with a Terrain
Model Added
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86
Surveying on an Ellipsoidal ERM
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87
Normal Section of an Ellipsoid
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88
Distance on an Ellipsoidal ERM
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89
Bearing Angles (Ellipsoidal ERM)
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90
Bearing when a Point P is above the ERM Surface
(Ellipsoid)
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91
Once the Environment is Included, There are
Many Feasible Paths
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92
Placing a Solid Cube on an ERM
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93
Doing the Math ...
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94
Placing a Cube on the Terrain Skin Model
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95
Long Linear Structures
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96
Vectors in Augmented Projection-based SRFs
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97
Vectors in a Curvilinear System
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98
Defining a Canonical Local Tangent Plane SRF
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99
A LTP Embedded in a GD SRF
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100
Defining a CLTP Embedded in a GD SRF
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101
Reference Vectors
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102
Reference Vector Transformations
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103
SRF “North” may not be True North
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104
Convergence of the Meridian
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105
Representing a Projection-based SRF Vector
in Terms of a CLTP
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106
TM series for X and Y (from P. D. Thomas)
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107
Computing the Convergence of the Meridian (COM)
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108
Second Method for Computing the COM
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109
Computing the Sine and Cosine of the COM
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110
Observations
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111
Section VII
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112
Why is Accuracy Needed for Coordinate Transformations?
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113
Shooting at a Target in the Real World (Relative
Coordinate System)
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114
Simulation of Shooting at a Target (Simulation
of a Relative Coordinate System)
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115
Error Sources in Coordinate Transformation
Software
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116
Definition of Error
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117
Numerical methods
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118
Efficient Evaluation of Special Functions Common
to Coordinate Transformations
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119
Analytic (closed form) Solutions
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120
Taylor/Maclaurin Series Methods
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121
Iterative Methods
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122
Direct Approximation of a Function or its Inverse
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123
Error in Power Series Expansions
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124
Authoritative Sources Sometimes Appear to Disagree
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125
Error Analysis and Resolution of Disagreements
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126
Effect of Small Errors
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127
Fuzzy Creep/Coordinate Drift
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128
Bounds Checking
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129
What to Do?
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130
Distortion and Computation Error Tradeoff
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131
Distortion in Projection-based SRFs
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132
Distortion-Accuracy Trades for UTM
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133
Point Scale Equations
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134
UTM Point Scale Equations
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135
Linear Distortion Error For UTM
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136
Difference between SR-7 & Extended Formulas
for Transverse Mercator
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137
Conclusions of Experiment
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138
The Chaining Problem
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139
Section VIII
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140
SRFs
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141
DRM <Location> (Page 15)
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142
SRFs Supported
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143
SRFs with CS Origin Offsets*
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144
Local Space Rectangular
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145
Local Space Rectangular (2D)
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146
Geocentric
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147
Geodetic
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148
Geodetic (2D)
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149
Local Tangent Plane
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150
Local Tangent Plane (2D)
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151
GCS
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152
Mercator
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153
Augmented Mercator
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154
Oblique Mercator
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155
Augm. Oblique Mercator
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156
Transverse Mercator
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157
Augm. Transverse Mercator
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158
Universal Transverse Mercator
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159
Augm. Univ. Transverse Mercator
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160
Lambert Conformal Conic
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161
Augm. Lambert Conformal Conic
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162
Polar Stereographic
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163
Augm. Polar Stereographic
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164
Universal Polar Stereographic
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165
Augm. Univ. Polar Stereographic
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166
Equidistant Cylindrical
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167
Augm. Equidistant Cylindrical
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168
Geocentric Equatorial Inertial
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169
Geomagnetic
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170
Geocentric Solar Ecliptic
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171
Geocentric Solar Magnetic
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172
Solar Magnetic
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173
Section IX
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174
PPT Slide
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175
ERM Datum Transformations
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176
Init WGS84 Geoidal Separation
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177
Get WGS84 Geoidal Separation
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178
PPT Slide
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179
Types of Operation Errors
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180
“Valid” Coordinates
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181
Coordinate Validity
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182
Implementation Details (1 of 2)
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183
Implementation Details (2 of 2)
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184
Range Extension (1 of 2)
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185
Range Extension (2 of 2)
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186
PPT Slide
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187
Op Support
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188
Coordinate Operation Chains
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189
Status Codes (1 of 3)
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190
Status Codes (2 of 3)
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191
Status Codes (3 of 3)
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192
Interface Specification(s)
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193
Operation Setup
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194
Conversion Operation
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195
Multi-conversion Operation
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196
Boundary Checking
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197
Operation Teardown
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198
Vector Operation
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199
Matrix Operation*
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200
Transformation Operation
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201
Convergence of Meridian Operation
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202
“SRM Check Utility”*
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203
Further Reading
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