Reference coordinate system determination

Abstract

A method of determining a reference coordinate system includes: obtaining information indicative of a direction of gravity relative to a device; and converting an orientation of a device coordinate system using the direction of gravity relative to the device to produce the reference coordinate system. The method may also include setting an origin of the reference coordinate system and/or determining a scale value of the reference coordinate system. The method may also include refining the reference coordinate system.

What is claimed is: 
     
         1 . A method of determining a reference coordinate system, the method comprising:
 obtaining information indicative of a direction of gravity relative to a device; and   converting an orientation of a device coordinate system using the direction of gravity relative to the device to produce the reference coordinate system.   
     
     
         2 . The method of  claim 1  further comprising obtaining information indicative of a direction perpendicular to gravity and wherein the converting comprises converting the orientation of the device coordinate system using the direction perpendicular to gravity. 
     
     
         3 . The method of  claim 2  wherein the direction perpendicular to gravity is one of magnetic north or a projection of a viewing direction of a camera of the device onto a plane perpendicular to gravity. 
     
     
         4 . The method of  claim 1  further comprising setting an origin of the reference coordinate system. 
     
     
         5 . The method of  claim 4  wherein setting the origin comprises:
 obtaining a point cloud; and 
 determining a geometric center of a substantially planar portion of the point cloud. 
 
     
     
         6 . The method of  claim 4  wherein setting the origin comprises:
 obtaining a point cloud; and 
 determining an intersection of a view direction of a camera of the device and a plane corresponding to a substantially planar portion of the point cloud. 
 
     
     
         7 . The method of  claim 1  further comprising calculating a scale value and producing the reference coordinate system using the scale value. 
     
     
         8 . The method of  claim 7  wherein calculating the scale value comprises:
 obtaining a point cloud; and 
 comparing a dimension of the point cloud to a fixed size. 
 
     
     
         9 . The method of  claim 7  wherein calculating the scale value comprises calculating the scale value such that an origin of the reference coordinate system will have a predetermined distance from the device. 
     
     
         10 . The method of  claim 7  wherein calculating the scale value comprises using absolute measurements from one or more input sensors of the device. 
     
     
         11 . The method of  claim 10  wherein the one or more input sensors comprise an accelerometer or a plurality of cameras. 
     
     
         12 . The method of  claim 1  further comprising refining the reference coordinate system using information from the reference coordinate system and at least one previously-determined coordinate system to generate a combination of the reference coordinate system and the at least one previously-determined coordinate system. 
     
     
         13 . The method of  claim 1  further comprising determining at least one of a first technique for converting the orientation or a second technique for setting an origin of the reference coordinate system based on an application for which the reference coordinate system is used. 
     
     
         14 . The method of  claim 1  wherein the reference coordinate system is an augmented reality coordinate system, the method further comprising displaying an augmented reality image disposed and directed in accordance with the reference coordinate system. 
     
     
         15 . A device for determining a reference coordinate system, the device comprising:
 means for obtaining information indicative of a direction of gravity relative to the device; and   means for converting an orientation of a device coordinate system using the direction of gravity relative to the device to produce the reference coordinate system.   
     
     
         16 . The device of  claim 15  further comprising means for obtaining information indicative of a direction perpendicular to gravity and wherein the means for converting are for converting the orientation of the device coordinate system using the direction perpendicular to gravity. 
     
     
         17 . The device of  claim 16  wherein the direction perpendicular to gravity is one of magnetic north or a projection of a viewing direction of a camera of the device onto a plane perpendicular to gravity. 
     
     
         18 . The device of  claim 15  further comprising means for setting an origin of the reference coordinate system. 
     
     
         19 . The device of  claim 18  wherein the means for setting the origin comprise:
 means for obtaining a point cloud; and 
 means for determining a geometric center of a substantially planar portion of the point cloud. 
 
     
     
         20 . The device of  claim 18  wherein the means for setting the origin comprise:
 means for obtaining a point cloud; and 
 means for determining an intersection of a view direction of a camera of the device and a plane corresponding to a substantially planar portion of the point cloud. 
 
     
     
         21 . The device of  claim 15  further comprising means for calculating a scale value such that an origin of the reference coordinate system will have a predetermined distance from the device. 
     
     
         22 . The device of  claim 21  wherein the means for calculating the scale value comprise:
 means for obtaining a point cloud; and 
 means for comparing a dimension of the point cloud to a fixed size. 
 
     
     
         23 . The device of  claim 21  wherein the means for calculating the scale value comprise means for calculating the scale value such that an origin of the reference coordinate system will have a predetermined distance from the device. 
     
     
         24 . The device of  claim 21  wherein the means for calculating the scale value comprise means for using absolute measurements from one or more input sensors of the device. 
     
     
         25 . The device of  claim 24  wherein the one or more input sensors comprise an accelerometer or a plurality of cameras. 
     
     
         26 . The device of  claim 15  further comprising means for refining the reference coordinate system using information from the reference coordinate system and at least one previously-determined coordinate system to generate a combination of the reference coordinate system and the at least one previously-determined coordinate system. 
     
     
         27 . The device of  claim 15  further comprising means for determining at least one of a first technique for converting the orientation or a second technique for setting an origin of the reference coordinate system based on an application for which the reference coordinate system is used. 
     
     
         28 . The device of  claim 15  wherein the reference coordinate system is an augmented reality coordinate system, the device further comprising means for displaying an augmented reality image disposed and directed in accordance with the reference coordinate system. 
     
     
         29 . A mobile device comprising:
 a sensor configured to determine a direction of gravity and to provide an indication of the direction of gravity relative to the mobile device; and   an orientation module communicatively coupled to the sensor and configured to convert an orientation of a device coordinate system, of the mobile device, using the indication of the direction of gravity relative to the mobile device to produce a reference coordinate system.   
     
     
         30 . The mobile device of  claim 29  wherein the orientation module is further configured to convert the orientation of the device coordinate system using a direction perpendicular to gravity. 
     
     
         31 . The mobile device of  claim 29  further comprising an origin module communicatively coupled to the orientation module and configured to set an origin of the reference coordinate system by obtaining a point cloud and at least one of:
 determining a geometric center of a substantially planar portion of the point cloud; or 
 determining an intersection of a view direction of a camera of the mobile device and a plane corresponding to a substantially planar portion of the point cloud. 
 
     
     
         32 . The mobile device of  claim 29  further comprising a scale module communicatively coupled to the orientation module and configured to set a scale value for the reference coordinate system relative to the device coordinate system by:
 (1) obtaining a point cloud and comparing a dimension of the point cloud to a fixed size; or 
 (2) calculating the scale value such that an origin of the reference coordinate system will have a predetermined distance from the mobile device; or 
 (3) using absolute measurements from one or more input sensors of the mobile device. 
 
     
     
         33 . The mobile device of  claim 29  wherein the orientation module is configured to produce a refined reference coordinate system using information from the reference coordinate system and at least one previously determined coordinate system. 
     
     
         34 . The mobile device of  claim 29  wherein the reference coordinate system is an augmented reality coordinate system, the mobile device further comprising a display and a processor configured to cause the display to display an augmented reality image disposed and directed in accordance with the reference coordinate system. 
     
     
         35 . A processor-readable storage medium of a mobile device, the storage medium comprising processor-readable instructions configured to cause a processor to:
 obtain an indication of a direction of gravity relative to the mobile device; and   convert an orientation of a device coordinate system, of the mobile device, using the indication of the direction of gravity relative to the mobile device to produce a reference coordinate system.