diff -Nru simgear-2020.3.5+dfsg/debian/changelog simgear-2020.3.6+dfsg/debian/changelog
--- simgear-2020.3.5+dfsg/debian/changelog	2020-12-26 20:58:34.000000000 +0000
+++ simgear-2020.3.6+dfsg/debian/changelog	2021-02-13 21:15:50.000000000 +0000
@@ -1,3 +1,11 @@
+simgear (1:2020.3.6+dfsg-1) unstable; urgency=medium
+
+  * New upstream release 2020.3.6+dfsg
+  * Drop patch fix-ftbfs-split_iterator.patch, upstream fixed this
+    with an auto type, instead.
+
+ -- Markus Wanner <markus@bluegap.ch>  Sat, 13 Feb 2021 22:15:50 +0100
+
 simgear (1:2020.3.5+dfsg-1) unstable; urgency=medium
 
   * New upstream version 2020.3.5+dfsg
diff -Nru simgear-2020.3.5+dfsg/debian/patches/fix-ftbfs-split_iterator.patch simgear-2020.3.6+dfsg/debian/patches/fix-ftbfs-split_iterator.patch
--- simgear-2020.3.5+dfsg/debian/patches/fix-ftbfs-split_iterator.patch	2020-12-26 20:58:34.000000000 +0000
+++ simgear-2020.3.6+dfsg/debian/patches/fix-ftbfs-split_iterator.patch	2021-02-07 19:22:28.000000000 +0000
@@ -1,14 +0,0 @@
---- a/simgear/props/props.cxx
-+++ b/simgear/props/props.cxx
-@@ -574,10 +574,8 @@
-            int last_index = -1)
- {
-   using namespace boost;
--  typedef split_iterator<typename range_result_iterator<Range>::type>
--    PathSplitIterator;
- 
--  PathSplitIterator itr
-+  auto itr
-     = make_split_iterator(path, first_finder("/", is_equal()));
-   if (*path.begin() == '/')
-     return find_node_aux(current->getRootNode(), itr, create, last_index);
diff -Nru simgear-2020.3.5+dfsg/debian/patches/series simgear-2020.3.6+dfsg/debian/patches/series
--- simgear-2020.3.5+dfsg/debian/patches/series	2020-12-26 20:58:34.000000000 +0000
+++ simgear-2020.3.6+dfsg/debian/patches/series	2021-02-07 19:22:47.000000000 +0000
@@ -5,4 +5,3 @@
 disable_network_tests.patch
 spelling_fixes.patch
 fix-ftbfs-on-armel-armhf.patch
-fix-ftbfs-split_iterator.patch
diff -Nru simgear-2020.3.5+dfsg/simgear/environment/metar.cxx simgear-2020.3.6+dfsg/simgear/environment/metar.cxx
--- simgear-2020.3.5+dfsg/simgear/environment/metar.cxx	2020-12-26 20:55:11.000000000 +0000
+++ simgear-2020.3.6+dfsg/simgear/environment/metar.cxx	2021-01-23 18:01:02.000000000 +0000
@@ -46,6 +46,7 @@
 #include <sstream>
 
 #include <simgear/debug/logstream.hxx>
+#include <simgear/math/sg_random.h>
 #include <simgear/structure/exception.hxx>
 
 #include "metar.hxx"
@@ -1068,9 +1069,12 @@
 		return false;
 	m += i;
 
-	if (!strncmp(m, "///", 3))	// vis not measurable (e.g. because of heavy snowing)
+	if (!strncmp(m, "///", 3))	{ // vis not measurable (e.g. because of heavy snowing)
 		m += 3, i = -1;
-	else if (scanBoundary(&m)) {
+		sg_srandom_time();
+		// randomize the base height to avoid the black sky issue
+		i = 50 + static_cast<int>(sg_random() * 250.0);		// range [5,000, 30,000]
+	} else if (scanBoundary(&m)) {
 		_m = m;
 		return true;				// ignore single OVC/BKN/...
 	} else if (!scanNumber(&m, &i, 3))
diff -Nru simgear-2020.3.5+dfsg/simgear/io/sg_binobj.cxx simgear-2020.3.6+dfsg/simgear/io/sg_binobj.cxx
--- simgear-2020.3.5+dfsg/simgear/io/sg_binobj.cxx	2020-12-26 20:55:11.000000000 +0000
+++ simgear-2020.3.6+dfsg/simgear/io/sg_binobj.cxx	2021-01-23 18:01:02.000000000 +0000
@@ -566,8 +566,10 @@
     sgReadUInt( fp, &header );
 
     if (sgReadError()) {
+        int code = 0;
+        const char* gzErrorString = gzerror(fp, &code);
         gzclose(fp);
-        throw sg_io_exception("Unable to read BTG header: " + simgear::strutils::error_string(errno), sg_location(file));
+        throw sg_io_exception("Unable to read BTG header: " + string{gzErrorString} + ", code =" + std::to_string(code), sg_location(file));
     }
 
     if ( ((header & 0xFF000000) >> 24) == 'S' &&
diff -Nru simgear-2020.3.5+dfsg/simgear/package/Root.cxx simgear-2020.3.6+dfsg/simgear/package/Root.cxx
--- simgear-2020.3.5+dfsg/simgear/package/Root.cxx	2020-12-26 20:55:11.000000000 +0000
+++ simgear-2020.3.6+dfsg/simgear/package/Root.cxx	2021-01-23 18:01:02.000000000 +0000
@@ -133,7 +133,9 @@
 
     void fireRefreshStatus(CatalogRef catalog, Delegate::StatusCode status)
     {
-        for (auto d : delegates) {
+        // take a copy of delegates since firing this can modify the data
+        const auto currentDelegates = delegates;
+        for (auto d : currentDelegates) {
             d->catalogRefreshed(catalog, status);
         }
     }
diff -Nru simgear-2020.3.5+dfsg/simgear/props/props.cxx simgear-2020.3.6+dfsg/simgear/props/props.cxx
--- simgear-2020.3.5+dfsg/simgear/props/props.cxx	2020-12-26 20:55:11.000000000 +0000
+++ simgear-2020.3.6+dfsg/simgear/props/props.cxx	2021-01-23 18:01:02.000000000 +0000
@@ -566,23 +566,15 @@
   }
 }
 #else
-template<typename Range>
-SGPropertyNode*
-find_node (SGPropertyNode * current,
-           const Range& path,
-           bool create,
-           int last_index = -1)
-{
+template <typename Range>
+SGPropertyNode *find_node(SGPropertyNode *current, const Range &path,
+                          bool create, int last_index = -1) {
   using namespace boost;
-  typedef split_iterator<typename range_result_iterator<Range>::type>
-    PathSplitIterator;
-
-  PathSplitIterator itr
-    = make_split_iterator(path, first_finder("/", is_equal()));
+  auto itr = make_split_iterator(path, first_finder("/", is_equal()));
   if (*path.begin() == '/')
     return find_node_aux(current->getRootNode(), itr, create, last_index);
-   else
-     return find_node_aux(current, itr, create, last_index);
+  else
+    return find_node_aux(current, itr, create, last_index);
 }
 #endif
 
diff -Nru simgear-2020.3.5+dfsg/simgear/scene/material/Effect.cxx simgear-2020.3.6+dfsg/simgear/scene/material/Effect.cxx
--- simgear-2020.3.5+dfsg/simgear/scene/material/Effect.cxx	2020-12-26 20:55:11.000000000 +0000
+++ simgear-2020.3.6+dfsg/simgear/scene/material/Effect.cxx	2021-01-23 18:01:03.000000000 +0000
@@ -76,7 +76,7 @@
 #include <simgear/structure/SGExpression.hxx>
 #include <simgear/props/props_io.hxx>
 #include <simgear/props/vectorPropTemplates.hxx>
-
+#include <simgear/debug/ErrorReportingCallback.hxx>
 #include <simgear/io/iostreams/sgstream.hxx>
 
 namespace simgear
@@ -928,7 +928,8 @@
         // FIXME orig: const string& shaderName = shaderKey.first;
         string shaderName = shaderKey.first;
         Shader::Type stype = (Shader::Type)shaderKey.second;
-        if (getPropertyRoot()->getBoolValue("/sim/version/compositor-support", false) &&
+        const bool compositorEnabled = getPropertyRoot()->getBoolValue("/sim/version/compositor-support", false);
+        if (compositorEnabled &&
             shaderName.substr(0, shaderName.find("/")) == "Shaders") {
             shaderName = "Compositor/" + shaderName;
         }
@@ -936,7 +937,9 @@
         if (fileName.empty())
         {
             SG_LOG(SG_INPUT, SG_ALERT, "Could not locate shader" << shaderName);
-
+            if (!compositorEnabled) {
+                reportError("Missing shader", shaderName);
+            }
 
             throw BuilderException(string("couldn't find shader ") +
                 shaderName);
diff -Nru simgear-2020.3.5+dfsg/simgear/scene/material/TextureBuilder.cxx simgear-2020.3.6+dfsg/simgear/scene/material/TextureBuilder.cxx
--- simgear-2020.3.5+dfsg/simgear/scene/material/TextureBuilder.cxx	2020-12-26 20:55:11.000000000 +0000
+++ simgear-2020.3.6+dfsg/simgear/scene/material/TextureBuilder.cxx	2021-01-23 18:01:03.000000000 +0000
@@ -273,11 +273,19 @@
         options->setLoadOriginHint(SGReaderWriterOptions::LoadOriginHint::ORIGIN_EFFECTS_NORMALIZED);
     else
         options->setLoadOriginHint(SGReaderWriterOptions::LoadOriginHint::ORIGIN_EFFECTS);
-#if OSG_VERSION_LESS_THAN(3,4,2)
-    result = osgDB::readImageFile(imageName, options);
-#else
-    result = osgDB::readRefImageFile(imageName, options);
-#endif
+
+    try {
+    #if OSG_VERSION_LESS_THAN(3,4,2)
+        result = osgDB::readImageFile(imageName, options);
+    #else
+        result = osgDB::readRefImageFile(imageName, options);
+    #endif
+    } catch (std::bad_alloc& ba) {
+        SG_LOG(SG_GL, SG_ALERT, "Bad allocation loading:" << imageName);
+        // todo: report low memory warning
+        return false;
+    }
+
     options->setLoadOriginHint(origLOH);
     osg::ref_ptr<osg::Image> image;
     if (result.success())
diff -Nru simgear-2020.3.5+dfsg/simgear/scene/model/animation.cxx simgear-2020.3.6+dfsg/simgear/scene/model/animation.cxx
--- simgear-2020.3.5+dfsg/simgear/scene/model/animation.cxx	2020-12-26 20:55:11.000000000 +0000
+++ simgear-2020.3.6+dfsg/simgear/scene/model/animation.cxx	2021-01-23 18:01:03.000000000 +0000
@@ -1135,16 +1135,8 @@
         double intPart;
         double rot = modf(rotation, &intPart);
         double angle = rot * 2.0 * osg::PI;
-        const SGVec3d& sgcenter = transform->getCenter();
-        const SGVec3d& sgaxis = transform->getAxis();
-        Matrixd mat = Matrixd::translate(-sgcenter[0], -sgcenter[1], -sgcenter[2])
-            * Matrixd::rotate(angle, sgaxis[0], sgaxis[1], sgaxis[2])
-            * Matrixd::translate(sgcenter[0], sgcenter[1], sgcenter[2])
-            * *cv->getModelViewMatrix();
-        ref_ptr<RefMatrix> refmat = new RefMatrix(mat);
-        cv->pushModelViewMatrix(refmat.get(), transform->getReferenceFrame());
+        transform->setAngleRad(angle);
         traverse(transform, nv);
-        cv->popModelViewMatrix();
     } else {
         traverse(transform, nv);
     }
diff -Nru simgear-2020.3.5+dfsg/simgear/scene/tgdb/SGBuildingBin.cxx simgear-2020.3.6+dfsg/simgear/scene/tgdb/SGBuildingBin.cxx
--- simgear-2020.3.5+dfsg/simgear/scene/tgdb/SGBuildingBin.cxx	2020-12-26 20:55:11.000000000 +0000
+++ simgear-2020.3.6+dfsg/simgear/scene/tgdb/SGBuildingBin.cxx	2021-01-23 18:01:03.000000000 +0000
@@ -441,6 +441,10 @@
       if (hash_pos != std::string::npos)
           line.resize(hash_pos);
 
+      if (line.empty()) {
+          continue; // skip blank lines
+      }
+
       // and process further
       std::stringstream in(line);
 
diff -Nru simgear-2020.3.5+dfsg/simgear/scene/tgdb/SGOceanTile.cxx simgear-2020.3.6+dfsg/simgear/scene/tgdb/SGOceanTile.cxx
--- simgear-2020.3.5+dfsg/simgear/scene/tgdb/SGOceanTile.cxx	2020-12-26 20:55:11.000000000 +0000
+++ simgear-2020.3.6+dfsg/simgear/scene/tgdb/SGOceanTile.cxx	2021-01-23 18:01:03.000000000 +0000
@@ -41,6 +41,7 @@
 #include <simgear/scene/material/EffectGeode.hxx>
 #include <simgear/scene/material/mat.hxx>
 #include <simgear/scene/material/matlib.hxx>
+#include <simgear/scene/model/BoundingVolumeBuildVisitor.hxx>
 #include <simgear/scene/util/OsgMath.hxx>
 #include <simgear/scene/util/VectorArrayAdapter.hxx>
 #include <simgear/scene/util/SGNodeMasks.hxx>
@@ -340,5 +341,10 @@
     transform->addChild(geode);
     transform->setNodeMask( ~(simgear::CASTSHADOW_BIT | simgear::MODELLIGHT_BIT) );
 
+    // Create a BVH at this point.  This is normally provided by the file loader, but as we create the 
+    // geometry programmatically, no file loader is involved.
+    BoundingVolumeBuildVisitor bvhBuilder(false);
+    transform->accept(bvhBuilder);
+    
     return transform;
 }
diff -Nru simgear-2020.3.5+dfsg/simgear-version simgear-2020.3.6+dfsg/simgear-version
--- simgear-2020.3.5+dfsg/simgear-version	2020-12-26 20:55:11.000000000 +0000
+++ simgear-2020.3.6+dfsg/simgear-version	2021-01-23 18:01:02.000000000 +0000
@@ -1 +1 @@
-2020.3.5
+2020.3.6