1 /*
2 * Copyright (C) 2019 Alberto Irurueta Carro (alberto@irurueta.com)
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package com.irurueta.navigation.frames;
17
18 /**
19 * Supported frames to describe position and orientation.
20 */
21 public enum FrameType {
22 /**
23 * Earth Centered Inertial frame (aka ECI frame) is an almost inertial frame (which means it does not accelerate
24 * or rotate with respect to the rest of the universe).
25 * This frame is nominally centered at the Earth's center of mass and oriented with respect to Earth's
26 * spin axis and the stars.
27 * The z-axis always points along the Earth's axis of rotation from the frame's origin at the center of
28 * mass to the true north pole (not the magnetic pole).
29 * The x- and y-axes lie within the equatorial plane, but do not rotate with Earth.
30 * The y-axis points 90º ahead of the x-axis in the direction of the Earth's rotation.
31 * The x-axis is defined as the direction from the Earth to the Sun at the vernal equinox, which is
32 * the spring equinox in the northern hemisphere.
33 * Because of Earth rotation and orbit around the Sun, axes of this frame are continuously in
34 * movement respect to Earth's surface.
35 */
36 EARTH_CENTERED_INERTIAL_FRAME,
37
38 /**
39 * Earth Centered Fixed frame (aka ECEF frame).
40 * This frame is similar to ECI frame except that all axes remain fixed with respect to the Earth's
41 * surface.
42 * ECEF is also centered at Earth's center of mass.
43 * The z-axis is the same as that of ECI's frame, pointing along Earth's axis of rotation from the
44 * center to the north pole (true not magnetic).
45 * The x-axis points from the center to the intersection of the equator with the IERS Reference
46 * Meridian (IRM) or Conventional Zero Meridian (CZM), which defines 0º longitude.
47 * The y-axis completes the right-handed orthogonal set, pointing from the center to the
48 * intersection of the equator with the 90º east meridian.
49 */
50 EARTH_CENTERED_EARTH_FIXED_FRAME,
51
52 /**
53 * Local Navigation frame.
54 * Its origin is the object described by the navigation solution. This could be part of the navigation
55 * system itself or the center of mass of the host vehicle or user.
56 * The axes are aligned with the topographic directions: north, east, and vertical.
57 * By convention the z-axis, also known as the down (D) axis, is defined as the normal to the surface
58 * of the reference ellipsoid in the direction pointing towards the Earth. Simple gravity models
59 * assume that the gravity vector is coincident with the z-axis of the corresponding local navigation
60 * frame. True gravity deviates from this slightly due to local anomalies.
61 * The x-axis, or north (N) axis, is the projection in the plane orthogonal to the z-axis of the line
62 * from the user to the North Pole.
63 * The y-axis completes the orthogonal set by pointing east and is known as the east (E) axis.
64 * North, east, down is the most common order of the axes in a local navigation coordinate system.
65 * This frame is also known as NED frame, standing for North, East and Down.
66 */
67 LOCAL_NAVIGATION_FRAME,
68
69 /**
70 * Local Tangent-Plane frame.
71 * Has a fixed origin with respect to the Earth, usually a point on the surface.
72 * Like the local navigation frame, its z-axis is aligned with the vertical (pointing either up or
73 * down). Its x- and y-axes may also be aligned with the topographic directions (i.e., north and east),
74 * in which case it may be known as a local geodecit frame or topocentric frame. However,
75 * the x- and y-axes may be also aligned with an environmental feature, such as a road or building.
76 * As with the other frames, the axes form a right-handed orthogonal set.
77 * This frame is Earth-fixed, but not Earth-centered.
78 * This type of frame is used for navigation within a localized area. Examples include aircraft
79 * landing and urban and indoor positioning.
80 * A planar frame, can be used for two-dimensional positioning, where its third dimension is
81 * neglected. It may comprise the horizontal components of the local tangent-plane frame or
82 * may be used to express projected coordinates.
83 */
84 LOCAL_TANGENT_PLANE_FRAME,
85
86 /**
87 * Body frame.
88 * Sometimes known as a vehicle frame.
89 * Comprises the origin and orientation of the object described by the navigation solution.
90 * The origin is coincident with that of the corresponding local navigation frame.
91 * However, the axes remain fixed with respect to the body.
92 * The most common convention is to set x-axis as the forward axis, pointing in the usual
93 * direction of travel, z is the down axis, pointing in the usual direction of gravity, and y
94 * is the right axis, completing the orthogonal set. For angular motion, the body-frame axes
95 * are also known as roll, pitch, and yaw. Roll motion is about the x-axis, pitch motion is
96 * about the y-axis, and yaw motion is about the z-axis.
97 */
98 BODY_FRAME
99 }