tracker/pt: add color extraction modes

7 files changed, 326 insertions, 108 deletions

diff --git a/tracker-pt/FTNoIR_PT_Controls.ui b/tracker-pt/FTNoIR_PT_Controls.ui
index 8d044654..ea83a215 100644
--- a/tracker-pt/FTNoIR_PT_Controls.ui
+++ b/tracker-pt/FTNoIR_PT_Controls.ui
@@ -9,8 +9,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>424</width>
-    <height>588</height>
+    <width>412</width>
+    <height>616</height>
    </rect>
   </property>
   <property name="sizePolicy">
@@ -36,20 +36,81 @@
    <property name="sizeConstraint">
     <enum>QLayout::SetFixedSize</enum>
    </property>
+   <item row="1" column="0" alignment="Qt::AlignVCenter">
+    <widget class="QGroupBox" name="groupBox_5">
+     <property name="sizePolicy">
+      <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+       <horstretch>0</horstretch>
+       <verstretch>0</verstretch>
+      </sizepolicy>
+     </property>
+     <property name="title">
+      <string>Status</string>
+     </property>
+     <layout class="QGridLayout" name="gridLayout_10">
+      <item row="1" column="0">
+       <widget class="QLabel" name="label_3">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+          <horstretch>0</horstretch>
+          <verstretch>0</verstretch>
+         </sizepolicy>
+        </property>
+        <property name="text">
+         <string>Extracted Points:</string>
+        </property>
+       </widget>
+      </item>
+      <item row="0" column="0">
+       <widget class="QLabel" name="label_38">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+          <horstretch>0</horstretch>
+          <verstretch>0</verstretch>
+         </sizepolicy>
+        </property>
+        <property name="text">
+         <string>Camera Info:</string>
+        </property>
+       </widget>
+      </item>
+      <item row="1" column="1">
+       <widget class="QLabel" name="pointinfo_label">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
+          <horstretch>0</horstretch>
+          <verstretch>0</verstretch>
+         </sizepolicy>
+        </property>
+        <property name="text">
+         <string/>
+        </property>
+       </widget>
+      </item>
+      <item row="0" column="1">
+       <widget class="QLabel" name="caminfo_label">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
+          <horstretch>0</horstretch>
+          <verstretch>0</verstretch>
+         </sizepolicy>
+        </property>
+        <property name="text">
+         <string/>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </item>
    <item row="0" column="0">
     <widget class="QTabWidget" name="tabWidget">
      <property name="sizePolicy">
-      <sizepolicy hsizetype="Preferred" vsizetype="MinimumExpanding">
+      <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
        <horstretch>0</horstretch>
        <verstretch>0</verstretch>
       </sizepolicy>
      </property>
-     <property name="minimumSize">
-      <size>
-       <width>0</width>
-       <height>0</height>
-      </size>
-     </property>
      <property name="locale">
       <locale language="English" country="UnitedStates"/>
      </property>
@@ -63,6 +124,12 @@
       <layout class="QVBoxLayout" name="verticalLayout">
        <item>
         <widget class="QGroupBox" name="groupBox">
+         <property name="sizePolicy">
+          <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+           <horstretch>0</horstretch>
+           <verstretch>0</verstretch>
+          </sizepolicy>
+         </property>
          <property name="title">
           <string>Camera settings</string>
          </property>
@@ -70,7 +137,7 @@
           <item row="0" column="1">
            <widget class="QComboBox" name="camdevice_combo">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -82,6 +149,12 @@
           </item>
           <item row="4" column="1">
            <widget class="QSpinBox" name="fov">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="suffix">
              <string>°</string>
             </property>
@@ -99,7 +172,7 @@
           <item row="4" column="0">
            <widget class="QLabel" name="label_4">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Expanding" vsizetype="Preferred">
+             <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -112,7 +185,7 @@
           <item row="1" column="0">
            <widget class="QLabel" name="label_36">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Expanding" vsizetype="Preferred">
+             <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -125,7 +198,7 @@
           <item row="3" column="0">
            <widget class="QLabel" name="label_37">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Expanding" vsizetype="Preferred">
+             <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -141,7 +214,7 @@
           <item row="2" column="1">
            <widget class="QSpinBox" name="res_y_spin">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -162,6 +235,12 @@
           </item>
           <item row="6" column="0">
            <widget class="QLabel" name="label_6">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="text">
              <string>Dynamic pose timeout</string>
             </property>
@@ -170,7 +249,7 @@
           <item row="3" column="1">
            <widget class="QSpinBox" name="fps_spin">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -188,6 +267,12 @@
           </item>
           <item row="5" column="1">
            <widget class="QCheckBox" name="dynamic_pose">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="text">
              <string/>
             </property>
@@ -196,7 +281,7 @@
           <item row="1" column="1">
            <widget class="QSpinBox" name="res_x_spin">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -218,7 +303,7 @@
           <item row="2" column="0">
            <widget class="QLabel" name="label_41">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Expanding" vsizetype="Preferred">
+             <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -230,6 +315,12 @@
           </item>
           <item row="6" column="1">
            <widget class="QSpinBox" name="init_phase_timeout">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="suffix">
              <string> ms</string>
             </property>
@@ -242,9 +333,9 @@
            </widget>
           </item>
           <item row="5" column="0">
-           <widget class="QLabel" name="label_5">
+           <widget class="QLabel" name="label_13">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Expanding" vsizetype="Preferred">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -257,7 +348,7 @@
           <item row="0" column="0">
            <widget class="QLabel" name="label_2">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Expanding" vsizetype="Preferred">
+             <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -285,22 +376,91 @@
           </item>
           <item row="7" column="0">
            <widget class="QLabel" name="label_9">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="text">
              <string>Camera settings (when available)</string>
             </property>
            </widget>
           </item>
+          <item row="5" column="0">
+           <widget class="QLabel" name="label_511111">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
+            <property name="text">
+             <string>Dynamic pose (for caps only, never clips)</string>
+            </property>
+           </widget>
+          </item>
+          <item row="8" column="0">
+           <widget class="QLabel" name="label_12">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Minimum" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
+            <property name="text">
+             <string>Color channels used</string>
+            </property>
+           </widget>
+          </item>
+          <item row="8" column="1">
+           <widget class="QComboBox" name="blob_color">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
+            <item>
+             <property name="text">
+              <string>Normal</string>
+             </property>
+            </item>
+            <item>
+             <property name="text">
+              <string>Floppy filter</string>
+             </property>
+            </item>
+            <item>
+             <property name="text">
+              <string>Red</string>
+             </property>
+            </item>
+           </widget>
+          </item>
          </layout>
         </widget>
        </item>
        <item>
         <widget class="QGroupBox" name="groupBox_2">
+         <property name="sizePolicy">
+          <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+           <horstretch>0</horstretch>
+           <verstretch>0</verstretch>
+          </sizepolicy>
+         </property>
          <property name="title">
           <string>Point extraction</string>
          </property>
          <layout class="QGridLayout" name="gridLayout_7">
           <item row="3" column="0">
            <widget class="QLabel" name="label_8">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="text">
              <string>Max size</string>
             </property>
@@ -311,6 +471,12 @@
           </item>
           <item row="1" column="0">
            <widget class="QLabel" name="label">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="text">
              <string>Threshold</string>
             </property>
@@ -321,6 +487,12 @@
           </item>
           <item row="2" column="0">
            <widget class="QLabel" name="label_7">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="text">
              <string>Min size</string>
             </property>
@@ -332,7 +504,7 @@
           <item row="1" column="1" colspan="2">
            <widget class="QSlider" name="threshold_slider">
             <property name="sizePolicy">
-             <sizepolicy hsizetype="Expanding" vsizetype="Maximum">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
               <horstretch>0</horstretch>
               <verstretch>0</verstretch>
              </sizepolicy>
@@ -362,6 +534,12 @@
           </item>
           <item row="0" column="0">
            <widget class="QLabel" name="label_11">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="text">
              <string>Automatic threshold</string>
             </property>
@@ -369,6 +547,12 @@
           </item>
           <item row="0" column="1">
            <widget class="QCheckBox" name="auto_threshold">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="text">
              <string>Enable, slider sets point size</string>
             </property>
@@ -376,6 +560,12 @@
           </item>
           <item row="3" column="1">
            <widget class="QDoubleSpinBox" name="maxdiam_spin">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="toolTip">
              <string>Maximum point diameter</string>
             </property>
@@ -392,6 +582,12 @@
           </item>
           <item row="2" column="1">
            <widget class="QDoubleSpinBox" name="mindiam_spin">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
             <property name="toolTip">
              <string>Minimum point diameter</string>
             </property>
@@ -1147,91 +1343,14 @@ Don't roll or change position.</string>
      </widget>
     </widget>
    </item>
-   <item row="2" column="0" alignment="Qt::AlignVCenter">
-    <widget class="QGroupBox" name="groupBox_5">
+   <item row="2" column="0">
+    <widget class="QDialogButtonBox" name="buttonBox">
      <property name="sizePolicy">
       <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
        <horstretch>0</horstretch>
        <verstretch>0</verstretch>
       </sizepolicy>
      </property>
-     <property name="title">
-      <string>Status</string>
-     </property>
-     <layout class="QGridLayout" name="gridLayout_10">
-      <item row="1" column="0">
-       <widget class="QLabel" name="label_3">
-        <property name="text">
-         <string>Extracted Points:</string>
-        </property>
-       </widget>
-      </item>
-      <item row="0" column="0">
-       <widget class="QLabel" name="label_38">
-        <property name="text">
-         <string>Camera Info:</string>
-        </property>
-       </widget>
-      </item>
-      <item row="1" column="1">
-       <widget class="QLabel" name="pointinfo_label">
-        <property name="sizePolicy">
-         <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
-          <horstretch>0</horstretch>
-          <verstretch>0</verstretch>
-         </sizepolicy>
-        </property>
-        <property name="minimumSize">
-         <size>
-          <width>120</width>
-          <height>15</height>
-         </size>
-        </property>
-        <property name="text">
-         <string/>
-        </property>
-       </widget>
-      </item>
-      <item row="0" column="1">
-       <widget class="QLabel" name="caminfo_label">
-        <property name="sizePolicy">
-         <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
-          <horstretch>0</horstretch>
-          <verstretch>0</verstretch>
-         </sizepolicy>
-        </property>
-        <property name="minimumSize">
-         <size>
-          <width>120</width>
-          <height>15</height>
-         </size>
-        </property>
-        <property name="text">
-         <string/>
-        </property>
-       </widget>
-      </item>
-     </layout>
-    </widget>
-   </item>
-   <item row="1" column="0">
-    <spacer name="verticalSpacer">
-     <property name="orientation">
-      <enum>Qt::Vertical</enum>
-     </property>
-     <property name="sizeType">
-      <enum>QSizePolicy::Expanding</enum>
-     </property>
-     <property name="sizeHint" stdset="0">
-      <size>
-       <width>20</width>
-       <height>0</height>
-      </size>
-     </property>
-    </spacer>
-   </item>
-   <item row="3" column="0">
-    <widget class="QDialogButtonBox" name="buttonBox">
      <property name="standardButtons">
       <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
      </property>
diff --git a/tracker-pt/ftnoir_tracker_pt_dialog.cpp b/tracker-pt/ftnoir_tracker_pt_dialog.cpp
index ccedeb78..fa159d34 100644
--- a/tracker-pt/ftnoir_tracker_pt_dialog.cpp
+++ b/tracker-pt/ftnoir_tracker_pt_dialog.cpp
@@ -81,6 +81,18 @@ TrackerDialog_PT::TrackerDialog_PT()
     poll_tracker_info_impl();
 
     connect(this, &TrackerDialog_PT::poll_tracker_info, this, &TrackerDialog_PT::poll_tracker_info_impl, Qt::DirectConnection);
+
+    static constexpr pt_color_type color_types[] = {
+        pt_color_normal,
+        pt_color_floppy_filter,
+        pt_color_red_only,
+    };
+
+    static constexpr unsigned color_type_sz = sizeof(color_types) / sizeof(*color_types);
+    for (unsigned k = 0; k < color_type_sz; k++)
+        ui.blob_color->setItemData(k, int(color_types[k]));
+
+    tie_setting(s.blob_color, ui.blob_color);
 }
 
 void TrackerDialog_PT::startstop_trans_calib(bool start)
diff --git a/tracker-pt/ftnoir_tracker_pt_settings.h b/tracker-pt/ftnoir_tracker_pt_settings.h
index 79c1e103..265d382e 100644
--- a/tracker-pt/ftnoir_tracker_pt_settings.h
+++ b/tracker-pt/ftnoir_tracker_pt_settings.h
@@ -11,6 +11,15 @@
 #include "options/options.hpp"
 using namespace options;
 
+enum pt_color_type
+{
+    // explicit values, gotta preserve the numbering in .ini
+    // don't reuse when removing some of the modes
+    pt_color_normal = 2,
+    pt_color_red_only = 3,
+    pt_color_floppy_filter = 4,
+};
+
 struct settings_pt : opts
 {
     value<QString> camera_name;
@@ -33,6 +42,7 @@ struct settings_pt : opts
     value<bool> dynamic_pose;
     value<int> init_phase_timeout;
     value<bool> auto_threshold;
+    value<pt_color_type> blob_color;
 
     settings_pt() :
         opts("tracker-pt"),
@@ -63,6 +73,7 @@ struct settings_pt : opts
         fov(b, "camera-fov", 56),
         dynamic_pose(b, "dynamic-pose-resolution", true),
         init_phase_timeout(b, "init-phase-timeout", 250),
-        auto_threshold(b, "automatic-threshold", true)
+        auto_threshold(b, "automatic-threshold", true),
+        blob_color(b, "blob-color", pt_color_normal)
     {}
 };
diff --git a/tracker-pt/point_extractor.cpp b/tracker-pt/point_extractor.cpp
index dc36fbe5..54514111 100644
--- a/tracker-pt/point_extractor.cpp
+++ b/tracker-pt/point_extractor.cpp
@@ -78,6 +78,28 @@ PointExtractor::PointExtractor()
     blobs.reserve(max_blobs);
 }
 
+void PointExtractor::separate_channels(cv::Mat const& orig, const int* order, int order_npairs)
+{
+    if (unlikely(ch[0].rows != orig.rows || ch[0].cols != orig.cols))
+    {
+        for (unsigned k = 0; k < 3; k++)
+        {
+            ch[k] = cv::Mat1b(orig.rows, orig.cols);
+            ch_float[k] = cv::Mat1f(orig.rows, orig.cols);
+        }
+        // extra channel is a scratch buffer
+        ch_float[3] = cv::Mat1f(orig.rows, orig.cols);
+    }
+
+    if (order == nullptr)
+        cv::split(orig, (cv::Mat*) ch);
+    else
+        cv::mixChannels(&orig, 1, (cv::Mat*) ch, order_npairs, order, order_npairs);
+
+    for (unsigned k = 0; k < 3; k++)
+        ch[k].convertTo(ch_float[k], CV_32F);
+}
+
 void PointExtractor::extract_points(const cv::Mat& frame, cv::Mat& preview_frame, std::vector<vec2>& points)
 {
     using std::sqrt;
@@ -92,8 +114,60 @@ void PointExtractor::extract_points(const cv::Mat& frame, cv::Mat& preview_frame
         frame_blobs = cv::Mat1b(frame.rows, frame.cols);
     }
 
-    // convert to grayscale
-    cv::cvtColor(frame, frame_gray, cv::COLOR_BGR2GRAY);
+    const pt_color_type color = s.blob_color;
+    if (color == pt_color_normal)
+    {
+        // convert to grayscale
+        // this operation is optimized
+        cv::cvtColor(frame, frame_gray, cv::COLOR_BGR2GRAY);
+    }
+    else
+    {
+        switch (color)
+        {
+        case pt_color_floppy_filter:
+        {
+            // weight for blue color
+            static constexpr float B = .8;
+            // single channel weight
+            static constexpr float A = 1./2;
+
+            static constexpr int from_to[] = {
+                0, 0,
+                1, 1
+            };
+
+            separate_channels(frame, from_to, 2);
+
+            ch_float[2] =   ch_float[0] * B * A // blue
+                          + ch_float[1] * (1 - B) * A; // green
+            ch_float[2].convertTo(frame_gray, CV_8U);
+
+            break;
+        }
+        case pt_color_red_only:
+        {
+            static constexpr int from_to[] = {
+                2, 0
+            };
+
+            separate_channels(frame, from_to, 1);
+
+            static constexpr float R = 3;
+
+            ch_float[1] = ch_float[0] * R; // red
+
+            ch_float[1].convertTo(frame_gray, CV_8U);
+
+            break;
+        }
+        default:
+            once_only(qDebug() << "wrong pt_color_type enum value" << int(color));
+            // don't violate POLA
+            cv::cvtColor(frame, frame_gray, cv::COLOR_BGR2GRAY);
+            break;
+        }
+    }
 
     const double region_size_min = s.min_point_size;
     const double region_size_max = s.max_point_size;
diff --git a/tracker-pt/point_extractor.h b/tracker-pt/point_extractor.h
index 5fbe9a45..193c06dc 100644
--- a/tracker-pt/point_extractor.h
+++ b/tracker-pt/point_extractor.h
@@ -46,8 +46,10 @@ private:
     cv::Mat frame_bin;
     cv::Mat hist;
     cv::Mat frame_blobs;
-
     std::vector<blob> blobs;
+    cv::Mat ch[3], ch_float[4];
+
+    void separate_channels(cv::Mat const& orig_frame, int const* order = nullptr, int order_cnt = -1);
 };
 
 } // ns impl
diff --git a/tracker-pt/point_tracker.cpp b/tracker-pt/point_tracker.cpp
index d2620dce..ae873ef6 100644
--- a/tracker-pt/point_tracker.cpp
+++ b/tracker-pt/point_tracker.cpp
@@ -33,7 +33,7 @@ static void set_row(mat33& m, int i, const vec3& v)
     m(i,2) = v[2];
 }
 
-PointModel::PointModel(settings_pt& s)
+PointModel::PointModel(const settings_pt& s)
 {
     set_model(s);
     // calculate u
@@ -47,7 +47,7 @@ PointModel::PointModel(settings_pt& s)
     P = 1/(s11*s22-s12*s12) * mat22(s22, -s12, -s12,  s11);
 }
 
-void PointModel::set_model(settings_pt& s)
+void PointModel::set_model(const settings_pt& s)
 {
     switch (s.active_model_panel)
     {
diff --git a/tracker-pt/point_tracker.h b/tracker-pt/point_tracker.h
index ebbbc801..2b142632 100644
--- a/tracker-pt/point_tracker.h
+++ b/tracker-pt/point_tracker.h
@@ -42,8 +42,8 @@ struct PointModel final
 
     enum Model { Clip, Cap, Custom };
 
-    PointModel(settings_pt& s);
-    void set_model(settings_pt& s);
+    PointModel(const settings_pt& s);
+    void set_model(const settings_pt& s);
     void get_d_order(const vec2* points, unsigned* d_order, const vec2& d) const;
 };