Graphics depth formats: Add confidence values
Supplement the dense and sparse depth image formats with
confidence values.
For {HAL_PIXEL_FORMAT_Y_16, HAL_DATASPACE_DEPTH}, use the 3 MSBs
for confidence.
For {HAL_PIXEL_FORMAT_BLOB, HAL_DATASPACE_DEPTH}, add a 4th float
value for confidence.
Bug: 20123879
Change-Id: Idc27081efec682a712ce77ccfec59328f298b944
diff --git a/include/system/graphics.h b/include/system/graphics.h
index da24fb8..ff3fd88 100644
--- a/include/system/graphics.h
+++ b/include/system/graphics.h
@@ -147,7 +147,8 @@
* When used with ANativeWindow, the dataSpace field describes the color
* space of the buffer, except that dataSpace field
* HAL_DATASPACE_DEPTH indicates that this buffer contains a depth
- * image where each sample is a distance value measured by a depth camera.
+ * image where each sample is a distance value measured by a depth camera,
+ * plus an associated confidence value.
*/
HAL_PIXEL_FORMAT_Y16 = 0x20363159,
@@ -481,25 +482,31 @@
* When locking a native buffer of the above format and dataSpace value,
* the vaddr pointer can be cast to this structure.
*
- * A variable-length list of (x,y,z) 3D points, as floats.
+ * A variable-length list of (x,y,z, confidence) 3D points, as floats. (x, y,
+ * z) represents a measured point's position, with the coordinate system defined
+ * by the data source. Confidence represents the estimated likelihood that this
+ * measurement is correct. It is between 0.f and 1.f, inclusive, with 1.f ==
+ * 100% confidence.
*
* @num_points is the number of points in the list
*
* @xyz_points is the flexible array of floating-point values.
- * It contains (num_points) * 3 floats.
+ * It contains (num_points) * 4 floats.
*
* For example:
* android_depth_points d = get_depth_buffer();
* struct {
- * float x; float y; float z;
+ * float x; float y; float z; float confidence;
* } firstPoint, lastPoint;
*
- * firstPoint.x = d.xyz_points[0];
- * firstPoint.y = d.xyz_points[1];
- * firstPoint.z = d.xyz_points[2];
- * lastPoint.x = d.xyz_points[(d.num_points - 1) * 3 + 0];
- * lastPoint.y = d.xyz_points[(d.num_points - 1) * 3 + 1];
- * lastPoint.z = d.xyz_points[(d.num_points - 1) * 3 + 2];
+ * firstPoint.x = d.xyzc_points[0];
+ * firstPoint.y = d.xyzc_points[1];
+ * firstPoint.z = d.xyzc_points[2];
+ * firstPoint.confidence = d.xyzc_points[3];
+ * lastPoint.x = d.xyzc_points[(d.num_points - 1) * 4 + 0];
+ * lastPoint.y = d.xyzc_points[(d.num_points - 1) * 4 + 1];
+ * lastPoint.z = d.xyzc_points[(d.num_points - 1) * 4 + 2];
+ * lastPoint.confidence = d.xyzc_points[(d.num_points - 1) * 4 + 3];
*/
struct android_depth_points {
@@ -508,7 +515,7 @@
/** reserved for future use, set to 0 by gralloc's (*lock)() */
uint32_t reserved[8];
- float xyz_points[];
+ float xyzc_points[];
};
/**
@@ -730,9 +737,18 @@
/*
* The buffer contains depth ranging measurements from a depth camera.
* This value is valid with formats:
- * HAL_PIXEL_FORMAT_Y16: 16-bit single channel depth image.
+ * HAL_PIXEL_FORMAT_Y16: 16-bit samples, consisting of a depth measurement
+ * and an associated confidence value. The 3 MSBs of the sample make
+ * up the confidence value, and the low 13 LSBs of the sample make up
+ * the depth measurement.
+ * For the confidence section, 0 means 100% confidence, 1 means 0%
+ * confidence. The mapping to a linear float confidence value between
+ * 0.f and 1.f can be obtained with
+ * float confidence = (((depthSample >> 13) - 1) & 0x7) / 7.0f;
+ * The depth measurement can be extracted simply with
+ * uint16_t range = (depthSample & 0x1FFF);
* HAL_PIXEL_FORMAT_BLOB: A depth point cloud, as
- * a variable-length float (x,y,z) coordinate point list.
+ * a variable-length float (x,y,z, confidence) coordinate point list.
* The point cloud will be represented with the android_depth_points
* structure.
*/