Added corner method as a setting (detail)

conf/modules/cv_opticflow.xml

@@ -43,6 +43,8 @@
       <define name="MAX_ITERATIONS" value="10" description="Maximum number of iterations the Lucas Kanade algorithm should take"/>
       <define name="THRESHOLD_VEC" value="2" description="TThreshold in subpixels when the iterations of Lucas Kanade should stop"/>
 
+      <define name="CORNER_METHOD" value="1" description="Method used to look for corners, exhaustive FAST (0) or ACT-FAST (1)."/>
+
       <!-- FAST9 corner detection parameters -->
       <define name="FAST9_ADAPTIVE" value="TRUE" description="Whether we should use and adapative FAST9 crner detection threshold"/>
       <define name="FAST9_THRESHOLD" value="20" description="FAST9 default threshold"/>
@@ -65,6 +67,7 @@
       <!-- Optical flow calculations parameters -->
       <dl_settings name="vision_calc">
       <dl_setting var="opticflow.method" min="0" step="1" max="1" module="computer_vision/opticflow_module" shortname="method" values="LK_Fast9|EdgeFlow" param="METHOD"/>
+      <dl_setting var="opticflow.corner_method" min="0" step="1" max="1" module="computer_vision/opticflow_module" shortname="corner_method" values="exhaustive-FAST|ACT-FAST" param="CORNER_METHOD"/>
         <dl_setting var="opticflow.window_size" module="computer_vision/opticflow_module" min="0" step="1" max="20" shortname="window_size" param="OPTICFLOW_WINDOW_SIZE"/>
         <dl_setting var="opticflow.search_distance" module="computer_vision/opticflow_module" min="0" step="1" max="50" shortname="search_distance" param="SEARCH_DISTANCE"/>
         <dl_setting var="opticflow.subpixel_factor" module="computer_vision/opticflow_module" min="0" step="10" max="1000" shortname="subpixel_factor" param="OPTICFLOW_SUBPIXEL_FACTOR"/>
@@ -89,7 +92,7 @@
         <dl_setting var="opticflow.actfast_long_step" module="computer_vision/opticflow_module" min="1" step="1" max="100" shortname="actfast_long_step" param="OPTICFLOW_ACTFAST_LONG_STEP"/>
         <dl_setting var="opticflow.actfast_short_step" module="computer_vision/opticflow_module" min="1" step="1" max="10" shortname="actfast_short_step" param="OPTICFLOW_ACTFAST_SHORT_STEP"/>
         <dl_setting var="opticflow.actfast_min_gradient" module="computer_vision/opticflow_module" min="1" step="1" max="255" shortname="actfast_min_gradient" param="OPTICFLOW_ACTFAST_MIN_GRADIENT"/>
-        <dl_setting var="opticflow.actfast_gradient_method" module="computer_vision/opticflow_module" min="1" step="1" max="1"  values="SIMPLE|SOBEL" shortname="actfast_gradient_method" param="OPTICFLOW_ACTFAST_GRADIENT_METHOD"/>        
+        <dl_setting var="opticflow.actfast_gradient_method" module="computer_vision/opticflow_module" min="0" step="1" max="1"  values="SIMPLE|SOBEL" shortname="actfast_gradient_method" param="OPTICFLOW_ACTFAST_GRADIENT_METHOD"/>        
 
         <!-- Changes pyramid level of lucas kanade optical flow. -->
         <dl_setting var="opticflow.pyramid_level" module="computer_vision/opticflow_module" min="0" step="1" max="10" shortname="pyramid_level" param="OPTICFLOW_PYRAMID_LEVEL"/>

sw/airborne/modules/computer_vision/opticflow/opticflow_calculator.c

@@ -51,10 +51,9 @@
 
 #define EXHAUSTIVE_FAST 0
 #define ACT_FAST 1
+// TODO: these are now adapted, but perhaps later could be a setting:
 uint16_t n_time_steps = 10;
 uint16_t n_agents = 25;
-// corner method:
-#define CORNER_METHOD 0
 
 // What methods are run to determine divergence, lateral flow, etc.
 // SIZE_DIV looks at line sizes and only calculates divergence
@@ -63,6 +62,12 @@ uint16_t n_agents = 25;
 // relative velocities in x, y, z (divergence / time to contact), the slope of the surface, and the surface roughness.
 #define LINEAR_FIT 1
 
+#ifndef OPTICFLOW_CORNER_METHOD
+// This can be estimated by total possible image height / total Field of view
+#define OPTICFLOW_CORNER_METHOD ACT_FAST
+#endif
+PRINT_CONFIG_VAR(OPTICFLOW_CORNER_METHOD)
+
 // Camera parameters (defaults are from an ARDrone 2)
 #ifndef OPTICFLOW_FOV_W
 #define OPTICFLOW_FOV_W 0.89360857702
@@ -273,7 +278,7 @@ void opticflow_calc_init(struct opticflow_t *opticflow)
   opticflow->fast9_rsize = 512;
   opticflow->fast9_ret_corners = calloc(opticflow->fast9_rsize, sizeof(struct point_t));
 
-
+  opticflow->corner_method = OPTICFLOW_CORNER_METHOD;
   opticflow->actfast_long_step = OPTICFLOW_ACTFAST_LONG_STEP;
   opticflow->actfast_short_step = OPTICFLOW_ACTFAST_SHORT_STEP;
   opticflow->actfast_min_gradient = OPTICFLOW_ACTFAST_MIN_GRADIENT;
@@ -342,7 +347,7 @@ bool calc_fast9_lukas_kanade(struct opticflow_t *opticflow, struct image_t *img,
     // needs to be set to 0 because result is now static
     result->corner_cnt = 0;
 
-    if (CORNER_METHOD == EXHAUSTIVE_FAST) {
+    if (opticflow->corner_method == EXHAUSTIVE_FAST) {
       // FAST corner detection
       // TODO: There is something wrong with fast9_detect destabilizing FPS. This problem is reduced with putting min_distance
       // to 0 (see defines), however a more permanent solution should be considered
@@ -352,7 +357,7 @@ bool calc_fast9_lukas_kanade(struct opticflow_t *opticflow, struct image_t *img,
                    &opticflow->fast9_ret_corners,
                    NULL);
 
-    } else if (CORNER_METHOD == ACT_FAST) {
+    } else if (opticflow->corner_method == ACT_FAST) {
       // ACT-FAST corner detection:
       act_fast(&opticflow->prev_img_gray, opticflow->fast9_threshold, &result->corner_cnt,
                &opticflow->fast9_ret_corners, n_agents, n_time_steps,
@@ -371,14 +376,14 @@ bool calc_fast9_lukas_kanade(struct opticflow_t *opticflow, struct image_t *img,
           opticflow->fast9_threshold--;
         }
 
-        if (CORNER_METHOD == ACT_FAST) {
+        if (opticflow->corner_method == ACT_FAST) {
           n_time_steps++;
           n_agents++;
         }
 
       } else if (result->corner_cnt > OPTICFLOW_MAX_TRACK_CORNERS * 2 && opticflow->fast9_threshold < FAST9_HIGH_THRESHOLD) {
         opticflow->fast9_threshold++;
-        if (CORNER_METHOD == ACT_FAST && n_time_steps > 5 && n_agents > 10) {
+        if (opticflow->corner_method == ACT_FAST && n_time_steps > 5 && n_agents > 10) {
           n_time_steps--;
           n_agents--;
         }

sw/airborne/modules/computer_vision/opticflow/opticflow_calculator.h

@@ -44,6 +44,7 @@ struct opticflow_t {
   struct image_t prev_img_gray;         ///< Previous gray image frame
 
   uint8_t method;                   ///< Method to use to calculate the optical flow
+  uint8_t corner_method;            ///< Method to use for determining where the corners are
   uint16_t window_size;               ///< Window size for the blockmatching algorithm (general value for all methods)
   uint16_t search_distance;           ///< Search distance for blockmatching alg.
   bool derotation;                    ///< Derotation switched on or off (depended on the quality of the gyroscope measurement)