diff --git a/panda/src/grutil/pfmFile.I b/panda/src/grutil/pfmFile.I
index 22a6b3dffc..938acb5d00 100755
--- a/panda/src/grutil/pfmFile.I
+++ b/panda/src/grutil/pfmFile.I
@@ -73,15 +73,15 @@ get_num_channels() const {
 //     Function: PfmFile::has_point
 //       Access: Published
 //  Description: Returns true if there is a valid point at x, y.  This
-//               always returns true unless the zero_special flag is
-//               enabled, in which case it returns false if the point
-//               at x, y is zero.
+//               always returns true unless a "no data" value has been
+//               set, in which case it returns false if the point at
+//               x, y is the "no data" value.
 ////////////////////////////////////////////////////////////////////
 INLINE bool PfmFile::
 has_point(int x, int y) const {
   if ((x >= 0 && x < _x_size) && 
       (y >= 0 && y < _y_size)) {
-    return (!_zero_special || _table[y * _x_size + x] != LPoint3::zero());
+    return (!_has_no_data_value || _table[y * _x_size + x] != _no_data_value);
   }
   return false;
 }
@@ -138,22 +138,64 @@ modify_point(int x, int y) {
 //  Description: Sets the zero_special flag.  When this flag is true,
 //               values of (0, 0, 0) in the pfm file are treated as a
 //               special case, and are not processed.
+//
+//               This is a special case of set_no_data_value().
 ////////////////////////////////////////////////////////////////////
 INLINE void PfmFile::
 set_zero_special(bool zero_special) {
-  _zero_special = zero_special;
+  if (zero_special) {
+    set_no_data_value(LPoint3::zero());
+  } else {
+    clear_no_data_value();
+  }
 }
 
 ////////////////////////////////////////////////////////////////////
-//     Function: PfmFile::get_zero_special
+//     Function: PfmFile::set_no_data_value
 //       Access: Published
-//  Description: Returns the zero_special flag.  When this flag is true,
-//               values of (0, 0, 0) in the pfm file are treated as a
-//               special case, and are not processed.
+//  Description: Sets the special value that means "no data" when it
+//               appears in the pfm file.
+////////////////////////////////////////////////////////////////////
+INLINE void PfmFile::
+set_no_data_value(const LPoint3 &no_data_value) {
+  _has_no_data_value = true;
+  _no_data_value = no_data_value;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: PfmFile::set_no_data_value
+//       Access: Published
+//  Description: Removes the special value that means "no data" when it
+//               appears in the pfm file.  All points will thus be
+//               considered valid.
+////////////////////////////////////////////////////////////////////
+INLINE void PfmFile::
+clear_no_data_value() {
+  _has_no_data_value = false;
+  _no_data_value = LPoint3::zero();
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: PfmFile::has_no_data_value
+//       Access: Published
+//  Description: Returns whether a "no data" value has been
+//               established by set_no_data_value().
 ////////////////////////////////////////////////////////////////////
 INLINE bool PfmFile::
-get_zero_special() const {
-  return _zero_special;
+has_no_data_value() const {
+  return _has_no_data_value;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: PfmFile::get_no_data_value
+//       Access: Published
+//  Description: If has_no_data_value() returns true, this returns the
+//               particular "no data" value.
+////////////////////////////////////////////////////////////////////
+INLINE const LPoint3 &PfmFile::
+get_no_data_value() const {
+  nassertr(_has_no_data_value, LPoint3::zero());
+  return _no_data_value;
 }
 
 ////////////////////////////////////////////////////////////////////
diff --git a/panda/src/grutil/pfmFile.cxx b/panda/src/grutil/pfmFile.cxx
index 24705ee3b7..8005bfc80b 100755
--- a/panda/src/grutil/pfmFile.cxx
+++ b/panda/src/grutil/pfmFile.cxx
@@ -36,7 +36,8 @@
 ////////////////////////////////////////////////////////////////////
 PfmFile::
 PfmFile() {
-  _zero_special = false;
+  _has_no_data_value = false;
+  _no_data_value = LPoint3::zero();
   _vis_inverse = false;
   _vis_2d = false;
   clear();
@@ -54,7 +55,8 @@ PfmFile(const PfmFile &copy) :
   _y_size(copy._y_size),
   _scale(copy._scale),
   _num_channels(copy._num_channels),
-  _zero_special(copy._zero_special),
+  _has_no_data_value(copy._has_no_data_value),
+  _no_data_value(copy._no_data_value),
   _vis_inverse(copy._vis_inverse),
   _vis_2d(copy._vis_2d)
 {
@@ -72,7 +74,8 @@ operator = (const PfmFile &copy) {
   _y_size = copy._y_size;
   _scale = copy._scale;
   _num_channels = copy._num_channels;
-  _zero_special = copy._zero_special;
+  _has_no_data_value = copy._has_no_data_value;
+  _no_data_value = copy._no_data_value;
   _vis_inverse = copy._vis_inverse;
   _vis_2d = copy._vis_2d;
 }
@@ -352,7 +355,7 @@ calc_average_point(LPoint3 &result, PN_stdfloat x, PN_stdfloat y, PN_stdfloat ra
   for (yi = min_y; yi <= max_y; ++yi) {
     for (xi = min_x; xi <= max_x; ++xi) {
       const LPoint3 &p = _table[yi * _x_size + xi];
-      if (_zero_special && p == LPoint3::zero()) {
+      if (_has_no_data_value && p == _no_data_value) {
         continue;
       }
 
@@ -413,7 +416,7 @@ calc_min_max(LVecBase3 &min_depth, LVecBase3 &max_depth) const {
   Table::const_iterator ti;
   for (ti = _table.begin(); ti != _table.end(); ++ti) {
     const LPoint3 &p = (*ti);
-    if (_zero_special && p == LPoint3::zero()) {
+    if (_has_no_data_value && p == _no_data_value) {
       continue;
     }
     
@@ -528,7 +531,7 @@ xform(const LMatrix4 &transform) {
 
   Table::iterator ti;
   for (ti = _table.begin(); ti != _table.end(); ++ti) {
-    if (_zero_special && (*ti) == LPoint3::zero()) {
+    if (_has_no_data_value && (*ti) == _no_data_value) {
       continue;
     }
 
@@ -558,7 +561,7 @@ project(const Lens *lens) {
   
   Table::iterator ti;
   for (ti = _table.begin(); ti != _table.end(); ++ti) {
-    if (_zero_special && (*ti) == LPoint3::zero()) {
+    if (_has_no_data_value && (*ti) == _no_data_value) {
       continue;
     }
 
@@ -582,13 +585,13 @@ merge(const PfmFile &other) {
   nassertv(is_valid() && other.is_valid());
   nassertv(other._x_size == _x_size && other._y_size == _y_size);
 
-  if (!_zero_special) {
+  if (!_has_no_data_value) {
     // Trivial no-op.
     return;
   }
 
   for (size_t i = 0; i < _table.size(); ++i) {
-    if (_table[i] == LPoint3::zero()) {
+    if (_table[i] == _no_data_value) {
       _table[i] = other._table[i];
     }
   }
@@ -701,7 +704,7 @@ compute_planar_bounds(const LPoint2 &center, PN_stdfloat point_dist, PN_stdfloat
   } else {
     Table::const_iterator ti;
     for (ti = _table.begin(); ti != _table.end(); ++ti) {
-      if (_zero_special && (*ti) == LPoint3::zero()) {
+      if (_has_no_data_value && (*ti) == _no_data_value) {
         continue;
       }
       LPoint3 point = (*ti) * rinv;
@@ -1042,11 +1045,11 @@ make_vis_mesh_geom(GeomNode *gnode, bool inverted) const {
       for (int yi = y_begin; yi < y_end - 1; ++yi) {
         for (int xi = x_begin; xi < x_end - 1; ++xi) {
 
-          if (_zero_special) {
-            if (get_point(xi, yi) == LPoint3::zero() ||
-                get_point(xi, yi + 1) == LPoint3::zero() ||
-                get_point(xi + 1, yi + 1) == LPoint3::zero() ||
-                get_point(xi + 1, yi) == LPoint3::zero()) {
+          if (_has_no_data_value) {
+            if (get_point(xi, yi) == _no_data_value ||
+                get_point(xi, yi + 1) == _no_data_value ||
+                get_point(xi + 1, yi + 1) == _no_data_value ||
+                get_point(xi + 1, yi) == _no_data_value) {
               continue;
             }
           }
@@ -1164,7 +1167,7 @@ void PfmFile::
 box_filter_point(LPoint3 &result, PN_stdfloat &coverage,
                  int x, int y, PN_stdfloat x_contrib, PN_stdfloat y_contrib) const {
   const LPoint3 &point = get_point(x, y);
-  if (_zero_special && point == LPoint3::zero()) {
+  if (_has_no_data_value && point == _no_data_value) {
     return;
   }
 
diff --git a/panda/src/grutil/pfmFile.h b/panda/src/grutil/pfmFile.h
index bb0f784e65..9694344a1a 100755
--- a/panda/src/grutil/pfmFile.h
+++ b/panda/src/grutil/pfmFile.h
@@ -59,7 +59,10 @@ PUBLISHED:
   BLOCKING bool calc_min_max(LVecBase3 &min_points, LVecBase3 &max_points) const;
 
   INLINE void set_zero_special(bool zero_special);
-  INLINE bool get_zero_special() const;
+  INLINE void set_no_data_value(const LPoint3 &no_data_value);
+  INLINE void clear_no_data_value();
+  INLINE bool has_no_data_value() const;
+  INLINE const LPoint3 &get_no_data_value() const;
 
   BLOCKING void resize(int new_x_size, int new_y_size);
   BLOCKING void reverse_rows();
@@ -118,7 +121,8 @@ private:
   PN_stdfloat _scale;
   int _num_channels;
 
-  bool _zero_special;
+  bool _has_no_data_value;
+  LPoint3 _no_data_value;
   bool _vis_inverse;
   PT(InternalName) _flat_texcoord_name;
   bool _vis_2d;