Set default value for half_block = 0 when reading ROOT files (#1012)

robbietuk · KrisThielemans · web-flow · commit ec0db7231915 · 2022-03-27T18:08:22.000+01:00
Set default value for half_block = 0 and introduce STIR_ROOT_ROTATION_AS_V4

Co-authored-by: Kris Thielemans &lt;KrisThielemans@users.noreply.github.com&gt;
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -141,6 +141,7 @@ endif()
 # Legacy options
 option(STIR_PROJECTORS_AS_V3 "Enable STIR version 3 legacy code" OFF)
 option(STIR_LEGACY_IGNORE_VIEW_OFFSET "Ignore using scanner view-offset (or intrinsic azimuthal tilt), as in STIR 4 or earlier" OFF)
+option(STIR_ROOT_ROTATION_AS_V4 "Ignore the changes to the ROOT rotation introduced in STIR version 5" OFF)
 
 # NiftyPET projector
 if(NOT DISABLE_NiftyPET_PROJECTOR OR NOT DISABLE_Parallelproj_PROJECTOR)
diff --git a/documentation/release_5.0.htm b/documentation/release_5.0.htm
@@ -339,6 +339,15 @@ <h3>Backward incompatibities</h3>
       scanners, this will fill in the detector maps etc.
       You will get a run-time exception if you forgot to do this.
     </li>
+    <li>
+        Rotational changes to STIR's interface to ROOT files, <a href=https://github.com/UCL/STIR/pull/1012>PR #1012</a>. In previous versions (roughly) half a bucket,
+        <code>(module_repeater_y * submodule_repeater_y * crystal_repeater_y) /2 - 1)</code>
+        in the <tt>Cylindrical</tt> case, was subtracted from the crystalIDs, in an attempt to rotate
+        the scanner. However, this was incompatible with the STIR code to find normalisation factors,
+        and could be surprising for odd numbers etc.
+        Rotations should use the new view offset support described above.
+        Backwards compatibility can be maintained with the CMake switch, <tt>STIR_ROOT_ROTATION_AS_V4</tt>.
+    </li>
 </ul>
 
 <h3>New functionality</h3>
diff --git a/src/IO/InputStreamFromROOTFileForCylindricalPET.cxx b/src/IO/InputStreamFromROOTFileForCylindricalPET.cxx
@@ -112,8 +112,10 @@ get_next_record(CListRecordROOT& record)
 
     // GATE counts crystal ID =0 the most negative. Therefore
     // ID = 0 should be negative, in Rsector 0 and the mid crystal ID be 0 .
+#if STIR_ROOT_ROTATION_AS_V4
     crystal1 -= half_block;
     crystal2 -= half_block;
+#endif
 
     // Add offset
     crystal1 += offset_dets;
@@ -146,6 +148,13 @@ InputStreamFromROOTFileForCylindricalPET::set_defaults()
     module_repeater_y = -1;
     module_repeater_z = -1;
     rsector_repeater = -1;
+#if STIR_ROOT_ROTATION_AS_V4
+    half_block = module_repeater_y * submodule_repeater_y * crystal_repeater_y / 2  - 1;
+    if (half_block < 0 )
+      half_block = 0;
+#else
+    half_block = 0;
+#endif
 }
 
 void
diff --git a/src/IO/InputStreamFromROOTFileForECATPET.cxx b/src/IO/InputStreamFromROOTFileForECATPET.cxx
@@ -96,8 +96,10 @@ get_next_record(CListRecordROOT& record)
 
     // GATE counts crystal ID =0 the most negative. Therefore
     // ID = 0 should be negative, in Rsector 0 and the mid crystal ID be 0 .
+#if STIR_ROOT_ROTATION_AS_V4
     crystal1 -= half_block;
     crystal2 -= half_block;
+#endif
 
     // Add offset
     crystal1 += offset_dets;
@@ -125,6 +127,13 @@ InputStreamFromROOTFileForECATPET::set_defaults()
     base_type::set_defaults();
     block_repeater_y = -1;
     block_repeater_z = -1;
+#if STIR_ROOT_ROTATION_AS_V4
+    half_block = crystal_repeater_y / 2  - 1;
+    if (half_block < 0 )
+        half_block = 0;
+#else
+    half_block = 0;
+#endif
 }
 
 void
diff --git a/src/cmake/STIRConfig.h.in b/src/cmake/STIRConfig.h.in
@@ -88,5 +88,6 @@ namespace stir {
 #endif
 
 #cmakedefine STIR_PROJECTORS_AS_V3
+#cmakedefine STIR_ROOT_ROTATION_AS_V4
 #cmakedefine STIR_LEGACY_IGNORE_VIEW_OFFSET
 #endif //  __stir_config__H__
