diff --git a/assignment-client/src/metavoxels/MetavoxelServer.cpp b/assignment-client/src/metavoxels/MetavoxelServer.cpp
index 622ae87ce6..314ffb28e4 100644
--- a/assignment-client/src/metavoxels/MetavoxelServer.cpp
+++ b/assignment-client/src/metavoxels/MetavoxelServer.cpp
@@ -35,14 +35,16 @@ void MetavoxelServer::applyEdit(const MetavoxelEditMessage& edit) {
     setData(data);
 }
 
-void MetavoxelServer::setData(const MetavoxelData& data) {
+void MetavoxelServer::setData(const MetavoxelData& data, bool loaded) {
     if (_data == data) {
         return;
     }    
     emit dataChanged(_data = data);
     
-    if (!_savedDataInitialized) {
+    if (loaded) {
         _savedData = data;
+    
+    } else if (!_savedDataInitialized) {        
         _savedDataInitialized = true;
         
         // start the save timer
@@ -340,7 +342,7 @@ void MetavoxelPersister::load() {
             debug << "failed, " << e.getDescription();
             return;
         }
-        QMetaObject::invokeMethod(_server, "setData", Q_ARG(const MetavoxelData&, data));
+        QMetaObject::invokeMethod(_server, "setData", Q_ARG(const MetavoxelData&, data), Q_ARG(bool, true));
         debug << "done.";
     }
     data.dumpStats();
diff --git a/assignment-client/src/metavoxels/MetavoxelServer.h b/assignment-client/src/metavoxels/MetavoxelServer.h
index a4facb5426..2d1529b1b1 100644
--- a/assignment-client/src/metavoxels/MetavoxelServer.h
+++ b/assignment-client/src/metavoxels/MetavoxelServer.h
@@ -36,7 +36,7 @@ public:
 
     const MetavoxelData& getData() const { return _data; }
     
-    Q_INVOKABLE void setData(const MetavoxelData& data);
+    Q_INVOKABLE void setData(const MetavoxelData& data, bool loaded = false);
 
     virtual void run();
     
diff --git a/libraries/metavoxels/src/Spanner.cpp b/libraries/metavoxels/src/Spanner.cpp
index 5166777db1..fd657903c3 100644
--- a/libraries/metavoxels/src/Spanner.cpp
+++ b/libraries/metavoxels/src/Spanner.cpp
@@ -613,7 +613,31 @@ static QByteArray encodeHeightfieldHeight(int offsetX, int offsetY, int width, i
     *header++ = offsetY;
     *header++ = width;
     *header++ = height;
-    inflated.append((const char*)contents.constData(), contents.size() * sizeof(quint16));
+    if (!contents.isEmpty()) {
+        // encode with Paeth filter (see http://en.wikipedia.org/wiki/Portable_Network_Graphics#Filtering)
+        QVector<quint16> filteredContents(contents.size());
+        const quint16* src = contents.constData();
+        quint16* dest = filteredContents.data();
+        *dest++ = *src++;
+        for (quint16* end = dest + width - 1; dest != end; dest++, src++) {
+            *dest = *src - src[-1];
+        }
+        for (int y = 1; y < height; y++) {
+            *dest++ = *src - src[-width];
+            src++;
+            for (quint16* end = dest + width - 1; dest != end; dest++, src++) {
+                int a = src[-1];
+                int b = src[-width];
+                int c = src[-width - 1];
+                int p = a + b - c;
+                int ad = abs(a - p);
+                int bd = abs(b - p);
+                int cd = abs(c - p);
+                *dest = *src - (ad < bd ? (ad < cd ? a : c) : (bd < cd ? b : c));
+            }
+        }  
+        inflated.append((const char*)filteredContents.constData(), filteredContents.size() * sizeof(quint16));
+    }
     return qCompress(inflated);
 }
 
@@ -626,9 +650,30 @@ static QVector<quint16> decodeHeightfieldHeight(const QByteArray& encoded, int&
     width = *header++;
     height = *header++;
     int payloadSize = inflated.size() - HEIGHTFIELD_DATA_HEADER_SIZE;
-    QVector<quint16> decoded(payloadSize / sizeof(quint16));
-    memcpy(decoded.data(), inflated.constData() + HEIGHTFIELD_DATA_HEADER_SIZE, payloadSize);
-    return decoded;
+    QVector<quint16> unfiltered(payloadSize / sizeof(quint16));
+    if (!unfiltered.isEmpty()) {
+        quint16* dest = unfiltered.data();
+        const quint16* src = (const quint16*)(inflated.constData() + HEIGHTFIELD_DATA_HEADER_SIZE);
+        *dest++ = *src++;
+        for (quint16* end = dest + width - 1; dest != end; dest++, src++) {
+            *dest = *src + dest[-1];
+        }
+        for (int y = 1; y < height; y++) {
+            *dest = (*src++) + dest[-width];
+            dest++;
+            for (quint16* end = dest + width - 1; dest != end; dest++, src++) {
+                int a = dest[-1];
+                int b = dest[-width];
+                int c = dest[-width - 1];
+                int p = a + b - c;
+                int ad = abs(a - p);
+                int bd = abs(b - p);
+                int cd = abs(c - p);
+                *dest = *src + (ad < bd ? (ad < cd ? a : c) : (bd < cd ? b : c));
+            }
+        }
+    }
+    return unfiltered;
 }
 
 HeightfieldHeight::HeightfieldHeight(int width, const QVector<quint16>& contents) :
@@ -861,13 +906,42 @@ void HeightfieldHeightEditor::clear() {
 }
 
 static QByteArray encodeHeightfieldColor(int offsetX, int offsetY, int width, int height, const QByteArray& contents) {
-    QByteArray inflated(HEIGHTFIELD_DATA_HEADER_SIZE, 0);
+    QByteArray inflated(HEIGHTFIELD_DATA_HEADER_SIZE + contents.size(), 0);
     qint32* header = (qint32*)inflated.data();
     *header++ = offsetX;
     *header++ = offsetY;
     *header++ = width;
     *header++ = height;
-    inflated.append(contents);
+    if (!contents.isEmpty()) {
+        // encode with Paeth filter (see http://en.wikipedia.org/wiki/Portable_Network_Graphics#Filtering)
+        const uchar* src = (const uchar*)contents.constData();
+        uchar* dest = (uchar*)inflated.data() + HEIGHTFIELD_DATA_HEADER_SIZE;
+        *dest++ = *src++;
+        *dest++ = *src++;
+        *dest++ = *src++;
+        int stride = width * DataBlock::COLOR_BYTES;
+        for (uchar* end = dest + stride - DataBlock::COLOR_BYTES; dest != end; dest++, src++) {
+            *dest = *src - src[-DataBlock::COLOR_BYTES];
+        }
+        for (int y = 1; y < height; y++) {
+            *dest++ = *src - src[-stride];
+            src++;
+            *dest++ = *src - src[-stride];
+            src++;
+            *dest++ = *src - src[-stride];
+            src++;
+            for (uchar* end = dest + stride - DataBlock::COLOR_BYTES; dest != end; dest++, src++) {
+                int a = src[-DataBlock::COLOR_BYTES];
+                int b = src[-stride];
+                int c = src[-stride - DataBlock::COLOR_BYTES];
+                int p = a + b - c;
+                int ad = abs(a - p);
+                int bd = abs(b - p);
+                int cd = abs(c - p);
+                *dest = *src - (ad < bd ? (ad < cd ? a : c) : (bd < cd ? b : c));
+            }
+        }
+    }
     return qCompress(inflated);
 }
 
@@ -878,7 +952,37 @@ static QByteArray decodeHeightfieldColor(const QByteArray& encoded, int& offsetX
     offsetY = *header++;
     width = *header++;
     height = *header++;
-    return inflated.mid(HEIGHTFIELD_DATA_HEADER_SIZE);
+    QByteArray contents(inflated.size() - HEIGHTFIELD_DATA_HEADER_SIZE, 0);
+    if (!contents.isEmpty()) {
+        const uchar* src = (const uchar*)inflated.constData() + HEIGHTFIELD_DATA_HEADER_SIZE;
+        uchar* dest = (uchar*)contents.data();
+        *dest++ = *src++;
+        *dest++ = *src++;
+        *dest++ = *src++;
+        int stride = width * DataBlock::COLOR_BYTES;
+        for (uchar* end = dest + stride - DataBlock::COLOR_BYTES; dest != end; dest++, src++) {
+            *dest = *src + dest[-DataBlock::COLOR_BYTES];
+        }
+        for (int y = 1; y < height; y++) {
+            *dest = (*src++) + dest[-stride];
+            dest++;
+            *dest = (*src++) + dest[-stride];
+            dest++;
+            *dest = (*src++) + dest[-stride];
+            dest++;
+            for (uchar* end = dest + stride - DataBlock::COLOR_BYTES; dest != end; dest++, src++) {
+                int a = dest[-DataBlock::COLOR_BYTES];
+                int b = dest[-stride];
+                int c = dest[-stride - DataBlock::COLOR_BYTES];
+                int p = a + b - c;
+                int ad = abs(a - p);
+                int bd = abs(b - p);
+                int cd = abs(c - p);
+                *dest = *src + (ad < bd ? (ad < cd ? a : c) : (bd < cd ? b : c));
+            }
+        }
+    }
+    return contents;
 }
 
 HeightfieldColor::HeightfieldColor(int width, const QByteArray& contents) :