Index: trunk/psModules/src/objects/models/pmModel_DEV.c
===================================================================
--- trunk/psModules/src/objects/models/pmModel_DEV.c	(revision 36089)
+++ trunk/psModules/src/objects/models/pmModel_DEV.c	(revision 36106)
@@ -117,5 +117,4 @@
 
     assert (isfinite(q));
-    assert (isfinite(f0));
 
     // only worry about the central pixels at most
@@ -129,4 +128,5 @@
 	f0 = pmModelCP_SersicSubpix (X, Y, PAR[PM_PAR_SXX], PAR[PM_PAR_SXY], PAR[PM_PAR_SYY], 4.0, Nsub);
     }   
+    assert (isfinite(f0));
 
     float f1 = PAR[PM_PAR_I0]*f0;
@@ -243,4 +243,12 @@
 bool PM_MODEL_GUESS (pmModel *model, pmSource *source, psImageMaskType maskVal, psImageMaskType markVal)
 {
+    // for the moment, we are going to require moments and KronFlux
+    if (!source->moments) return false;
+    pmMoments *moments = source->moments;
+
+    if (!isfinite(moments->KronFlux)) return false;
+    if (!isfinite(moments->Mrf)) return false;
+    if (moments->Mrf < 0.0) return false;
+
     psF32 *PAR  = model->params->data.F32;
 
@@ -248,13 +256,31 @@
     PAR[PM_PAR_SKY]  = 0.0;
 
-    // set the shape parameters
-    if (!pmModelSetShape(&PAR[PM_PAR_SXX], &PAR[PM_PAR_SXY], &PAR[PM_PAR_SYY], source->moments, true)) {
-      return false;
-    }
-
-    // set the model normalization
-    if (!pmModelSetNorm(&PAR[PM_PAR_I0], source)) {
-      return false;
-    }
+    psEllipseMoments emoments;
+    emoments.x2 = moments->Mxx;
+    emoments.xy = moments->Mxy;
+    emoments.y2 = moments->Myy;
+
+    // force the axis ratio to be < 20.0
+    psEllipseAxes axes = psEllipseMomentsToAxes (emoments, 20.0);
+
+    if (!isfinite(axes.major)) return false;
+    if (!isfinite(axes.minor)) return false;
+    if (!isfinite(axes.theta)) return false;
+
+    // Mxx, Mxy, Myy define the elliptical shape, but Mrf defines the width 
+    float scale = moments->Mrf / axes.major;
+    axes.major *= scale;
+    axes.minor *= scale;
+
+    pmModelAxesToParams (&PAR[PM_PAR_SXX], &PAR[PM_PAR_SXY], &PAR[PM_PAR_SYY], axes, true);
+
+    // psEllipseAxes axes;
+    // use the code in SetShape here to avoid doing this 2x
+    // pmModelParamsToAxes (&axes, PAR[PM_PAR_SXX], PAR[PM_PAR_SXY], PAR[PM_PAR_SYY], true);
+
+    // float norm = pmSersicNorm (4);  // hardwire
+    float norm = 0.00168012;
+    float normFlux = 2.0 * M_PI * axes.major * axes.minor * norm;
+    PAR[PM_PAR_I0] = moments->KronFlux / normFlux;
 
     // set the model position
Index: trunk/psModules/src/objects/models/pmModel_EXP.c
===================================================================
--- trunk/psModules/src/objects/models/pmModel_EXP.c	(revision 36089)
+++ trunk/psModules/src/objects/models/pmModel_EXP.c	(revision 36106)
@@ -237,4 +237,12 @@
 bool PM_MODEL_GUESS (pmModel *model, pmSource *source, psImageMaskType maskVal, psImageMaskType markVal)
 {
+    // for the moment, we are going to require moments and KronFlux
+    if (!source->moments) return false;
+    pmMoments *moments = source->moments;
+
+    if (!isfinite(moments->KronFlux)) return false;
+    if (!isfinite(moments->Mrf)) return false;
+    if (moments->Mrf < 0.0) return false;
+
     psF32 *PAR  = model->params->data.F32;
 
@@ -242,13 +250,31 @@
     PAR[PM_PAR_SKY]  = 0.0;
 
-    // set the shape parameters
-    if (!pmModelSetShape(&PAR[PM_PAR_SXX], &PAR[PM_PAR_SXY], &PAR[PM_PAR_SYY], source->moments, true)) {
-      return false;
-    }
-
-    // set the model normalization
-    if (!pmModelSetNorm(&PAR[PM_PAR_I0], source)) {
-      return false;
-    }
+    psEllipseMoments emoments;
+    emoments.x2 = moments->Mxx;
+    emoments.xy = moments->Mxy;
+    emoments.y2 = moments->Myy;
+
+    // force the axis ratio to be < 20.0
+    psEllipseAxes axes = psEllipseMomentsToAxes (emoments, 20.0);
+
+    if (!isfinite(axes.major)) return false;
+    if (!isfinite(axes.minor)) return false;
+    if (!isfinite(axes.theta)) return false;
+
+    // Mxx, Mxy, Myy define the elliptical shape, but Mrf defines the width 
+    float scale = moments->Mrf / axes.major;
+    axes.major *= scale;
+    axes.minor *= scale;
+
+    pmModelAxesToParams (&PAR[PM_PAR_SXX], &PAR[PM_PAR_SXY], &PAR[PM_PAR_SYY], axes, true);
+
+    // psEllipseAxes axes;
+    // use the code in SetShape here to avoid doing this 2x
+    // pmModelParamsToAxes (&axes, PAR[PM_PAR_SXX], PAR[PM_PAR_SXY], PAR[PM_PAR_SYY], true);
+
+    // float norm = pmSersicNorm (4);  // hardwire
+    float norm = 0.34578;
+    float normFlux = 2.0 * M_PI * axes.major * axes.minor * norm;
+    PAR[PM_PAR_I0] = moments->KronFlux / normFlux;
 
     // set the model position
@@ -259,5 +285,4 @@
     return(true);
 }
-
 // An exponential model is equivalent to a Sersic with index = 1.0
 psF64 PM_MODEL_FLUX (const psVector *params)