Camera: Documentation updates for calibration and distortion correction

     * <p>If this device is the largest or only camera device with a given facing, then this

     * position will be <code>(0, 0, 0)</code>; a camera device with a lens optical center located 3 cm

     * from the main sensor along the +X axis (to the right from the user's perspective) will

     * report <code>(0.03, 0, 0)</code>.</p>

     * report <code>(0.03, 0, 0)</code>.  Note that this means that, for many computer vision

     * applications, the position needs to be negated to convert it to a translation from the

     * camera to the origin.</p>

     * <p>To transform a pixel coordinates between two cameras facing the same direction, first

     * the source camera ACAMERA_LENS_DISTORTION must be corrected for.  Then the source

     * camera ACAMERA_LENS_INTRINSIC_CALIBRATION needs to be applied, followed by the

     * <p>To compare this against a real image from the destination camera, the destination camera

     * image then needs to be corrected for radial distortion before comparison or sampling.</p>

     * <p>When ACAMERA_LENS_POSE_REFERENCE is GYROSCOPE, then this position is relative to

     * the center of the primary gyroscope on the device.</p>

     * the center of the primary gyroscope on the device. The axis definitions are the same as

     * with PRIMARY_CAMERA.</p>

     *

     * @see ACAMERA_LENS_DISTORTION

     * @see ACAMERA_LENS_INTRINSIC_CALIBRATION

     * </code></pre>

     * <p>which can then be combined with the camera pose rotation

     * <code>R</code> and translation <code>t</code> (ACAMERA_LENS_POSE_ROTATION and

     * ACAMERA_LENS_POSE_TRANSLATION, respective) to calculate the

     * ACAMERA_LENS_POSE_TRANSLATION, respectively) to calculate the

     * complete transform from world coordinates to pixel

     * coordinates:</p>

     * <pre><code>P = [ K 0   * [ R t

     * <pre><code>P = [ K 0   * [ R -Rt

     *      0 1 ]      0 1 ]

     * </code></pre>

     * <p>and with <code>p_w</code> being a point in the world coordinate system

     * <p>(Note the negation of poseTranslation when mapping from camera

     * to world coordinates, and multiplication by the rotation).</p>

     * <p>With <code>p_w</code> being a point in the world coordinate system

     * and <code>p_s</code> being a point in the camera active pixel array

     * coordinate system, and with the mapping including the

     * homogeneous division by z:</p>

     * activeArraySize rectangle), to determine the final pixel

     * coordinate of the world point for processed (non-RAW)

     * output buffers.</p>

     * <p>For camera devices, the center of pixel <code>(x,y)</code> is located at

     * coordinate <code>(x + 0.5, y + 0.5)</code>.  So on a device with a

     * precorrection active array of size <code>(10,10)</code>, the valid pixel

     * indices go from <code>(0,0)-(9,9)</code>, and an perfectly-built camera would

     * have an optical center at the exact center of the pixel grid, at

     * coordinates <code>(5.0, 5.0)</code>, which is the top-left corner of pixel

     * <code>(5,5)</code>.</p>

     *

     * @see ACAMERA_LENS_DISTORTION

     * @see ACAMERA_LENS_POSE_ROTATION

     * outputs will crop horizontally (pillarbox), and 16:9

     * streams will match exactly. These additional crops will

     * be centered within the crop region.</p>

     * <p>If the coordinate system is android.sensor.info.activeArraysSize, the width and height

     * <p>If the coordinate system is ACAMERA_SENSOR_INFO_ACTIVE_ARRAY_SIZE, the width and height

     * of the crop region cannot be set to be smaller than

     * <code>floor( activeArraySize.width / ACAMERA_SCALER_AVAILABLE_MAX_DIGITAL_ZOOM )</code> and

     * <code>floor( activeArraySize.height / ACAMERA_SCALER_AVAILABLE_MAX_DIGITAL_ZOOM )</code>, respectively.</p>

    ACAMERA_STATISTICS_LENS_SHADING_MAP_MODE =                  // byte (acamera_metadata_enum_android_statistics_lens_shading_map_mode_t)

            ACAMERA_STATISTICS_START + 16,

    /**

     * <p>A control for selecting whether OIS position information is included in output

     * result metadata.</p>

     * <p>A control for selecting whether optical stabilization (OIS) position

     * information is included in output result metadata.</p>

     *

     * <p>Type: byte (acamera_metadata_enum_android_statistics_ois_data_mode_t)</p>

     *

     *   <li>ACaptureRequest</li>

     * </ul></p>

     *

     * <p>Since optical image stabilization generally involves motion much faster than the duration

     * of individualq image exposure, multiple OIS samples can be included for a single capture

     * result. For example, if the OIS reporting operates at 200 Hz, a typical camera operating

     * at 30fps may have 6-7 OIS samples per capture result. This information can be combined

     * with the rolling shutter skew to account for lens motion during image exposure in

     * post-processing algorithms.</p>

     */

    ACAMERA_STATISTICS_OIS_DATA_MODE =                          // byte (acamera_metadata_enum_android_statistics_ois_data_mode_t)

            ACAMERA_STATISTICS_START + 17,

     * </ul></p>

     *

     * <p>The array contains the amount of shifts in x direction, in pixels, based on OIS samples.

     * A positive value is a shift from left to right in active array coordinate system. For

     * example, if the optical center is (1000, 500) in active array coordinates, a shift of

     * (3, 0) puts the new optical center at (1003, 500).</p>

     * A positive value is a shift from left to right in the pre-correction active array

     * coordinate system. For example, if the optical center is (1000, 500) in pre-correction

     * active array coordinates, a shift of (3, 0) puts the new optical center at (1003, 500).</p>

     * <p>The number of shifts must match the number of timestamps in

     * ACAMERA_STATISTICS_OIS_TIMESTAMPS.</p>

     * <p>The OIS samples are not affected by whether lens distortion correction is enabled (on

     * supporting devices). They are always reported in pre-correction active array coordinates,

     * since the scaling of OIS shifts would depend on the specific spot on the sensor the shift

     * is needed.</p>

     *

     * @see ACAMERA_STATISTICS_OIS_TIMESTAMPS

     */

     * </ul></p>

     *

     * <p>The array contains the amount of shifts in y direction, in pixels, based on OIS samples.

     * A positive value is a shift from top to bottom in active array coordinate system. For

     * example, if the optical center is (1000, 500) in active array coordinates, a shift of

     * (0, 5) puts the new optical center at (1000, 505).</p>

     * A positive value is a shift from top to bottom in pre-correction active array coordinate

     * system. For example, if the optical center is (1000, 500) in active array coordinates, a

     * shift of (0, 5) puts the new optical center at (1000, 505).</p>

     * <p>The number of shifts must match the number of timestamps in

     * ACAMERA_STATISTICS_OIS_TIMESTAMPS.</p>

     * <p>The OIS samples are not affected by whether lens distortion correction is enabled (on

     * supporting devices). They are always reported in pre-correction active array coordinates,

     * since the scaling of OIS shifts would depend on the specific spot on the sensor the shift

     * is needed.</p>

     *

     * @see ACAMERA_STATISTICS_OIS_TIMESTAMPS

     */

     * any correction at all would slow down capture rate.  Every output stream will have a

     * similar amount of enhancement applied.</p>

     * <p>The correction only applies to processed outputs such as YUV, JPEG, or DEPTH16; it is not

     * applied to any RAW output. Metadata coordinates such as face rectangles or metering

     * regions are also not affected by correction.</p>

     * applied to any RAW output.</p>

     * <p>This control will be on by default on devices that support this control. Applications

     * disabling distortion correction need to pay extra attention with the coordinate system of

     * metering regions, crop region, and face rectangles. When distortion correction is OFF,

     * metadata coordinates follow the coordinate system of

     * ACAMERA_SENSOR_INFO_PRE_CORRECTION_ACTIVE_ARRAY_SIZE. When distortion is not OFF, metadata

     * coordinates follow the coordinate system of ACAMERA_SENSOR_INFO_ACTIVE_ARRAY_SIZE.</p>

     * coordinates follow the coordinate system of ACAMERA_SENSOR_INFO_ACTIVE_ARRAY_SIZE.  The

     * camera device will map these metadata fields to match the corrected image produced by the

     * camera device, for both capture requests and results.  However, this mapping is not very

     * precise, since rectangles do not generally map to rectangles when corrected.  Only linear

     * scaling between the active array and precorrection active array coordinates is

     * performed. Applications that require precise correction of metadata need to undo that

     * linear scaling, and apply a more complete correction that takes into the account the app's

     * own requirements.</p>

     * <p>The full list of metadata that is affected in this way by distortion correction is:</p>

     * <ul>

     * <li>ACAMERA_CONTROL_AF_REGIONS</li>

     * <li>ACAMERA_CONTROL_AE_REGIONS</li>

     * <li>ACAMERA_CONTROL_AWB_REGIONS</li>

     * <li>ACAMERA_SCALER_CROP_REGION</li>

     * <li>android.statistics.faces</li>

     * </ul>

     *

     * @see ACAMERA_CONTROL_AE_REGIONS

     * @see ACAMERA_CONTROL_AF_REGIONS

     * @see ACAMERA_CONTROL_AWB_REGIONS

     * @see ACAMERA_LENS_DISTORTION

     * @see ACAMERA_SCALER_CROP_REGION

     * @see ACAMERA_SENSOR_INFO_ACTIVE_ARRAY_SIZE

     * @see ACAMERA_SENSOR_INFO_PRE_CORRECTION_ACTIVE_ARRAY_SIZE

     */