diff --git a/src/cv/bsdfinterp.c b/src/cv/bsdfinterp.c
index 852b86a76..33abc5e44 100644
--- a/src/cv/bsdfinterp.c
+++ b/src/cv/bsdfinterp.c
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: bsdfinterp.c,v 2.16 2014/02/18 16:06:51 greg Exp $";
+static const char RCSid[] = "$Id: bsdfinterp.c,v 2.17 2014/02/19 05:16:06 greg Exp $";
 #endif
 /*
  * Interpolate BSDF data from radial basis functions in advection mesh.
@@ -262,92 +262,6 @@ get_interp(MIGRATION *miga[3], FVECT invec)
 	}
 }
 
-/* Advect and allocate new RBF along edge */
-static RBFNODE *
-e_advect_rbf(const MIGRATION *mig, const FVECT invec, int lobe_lim)
-{
-	double		cthresh = FTINY;
-	RBFNODE		*rbf;
-	int		n, i, j;
-	double		t, full_dist;
-						/* get relative position */
-	t = Acos(DOT(invec, mig->rbfv[0]->invec));
-	if (t < M_PI/grid_res) {		/* near first DSF */
-		n = sizeof(RBFNODE) + sizeof(RBFVAL)*(mig->rbfv[0]->nrbf-1);
-		rbf = (RBFNODE *)malloc(n);
-		if (rbf == NULL)
-			goto memerr;
-		memcpy(rbf, mig->rbfv[0], n);	/* just duplicate */
-		rbf->next = NULL; rbf->ejl = NULL;
-		return(rbf);
-	}
-	full_dist = acos(DOT(mig->rbfv[0]->invec, mig->rbfv[1]->invec));
-	if (t > full_dist-M_PI/grid_res) {	/* near second DSF */
-		n = sizeof(RBFNODE) + sizeof(RBFVAL)*(mig->rbfv[1]->nrbf-1);
-		rbf = (RBFNODE *)malloc(n);
-		if (rbf == NULL)
-			goto memerr;
-		memcpy(rbf, mig->rbfv[1], n);	/* just duplicate */
-		rbf->next = NULL; rbf->ejl = NULL;
-		return(rbf);
-	}
-	t /= full_dist;
-tryagain:
-	n = 0;					/* count migrating particles */
-	for (i = 0; i < mtx_nrows(mig); i++)
-	    for (j = 0; j < mtx_ncols(mig); j++)
-		n += (mtx_coef(mig,i,j) > cthresh);
-						/* are we over our limit? */
-	if ((lobe_lim > 0) & (n > lobe_lim)) {
-		cthresh = cthresh*2. + 10.*FTINY;
-		goto tryagain;
-	}
-#ifdef DEBUG
-	fprintf(stderr, "Input RBFs have %d, %d nodes -> output has %d\n",
-			mig->rbfv[0]->nrbf, mig->rbfv[1]->nrbf, n);
-#endif
-	rbf = (RBFNODE *)malloc(sizeof(RBFNODE) + sizeof(RBFVAL)*(n-1));
-	if (rbf == NULL)
-		goto memerr;
-	rbf->next = NULL; rbf->ejl = NULL;
-	VCOPY(rbf->invec, invec);
-	rbf->nrbf = n;
-	rbf->vtotal = 1.-t + t*mig->rbfv[1]->vtotal/mig->rbfv[0]->vtotal;
-	n = 0;					/* advect RBF lobes */
-	for (i = 0; i < mtx_nrows(mig); i++) {
-	    const RBFVAL	*rbf0i = &mig->rbfv[0]->rbfa[i];
-	    const float		peak0 = rbf0i->peak;
-	    const double	rad0 = R2ANG(rbf0i->crad);
-	    FVECT		v0;
-	    float		mv;
-	    ovec_from_pos(v0, rbf0i->gx, rbf0i->gy);
-	    for (j = 0; j < mtx_ncols(mig); j++)
-		if ((mv = mtx_coef(mig,i,j)) > cthresh) {
-			const RBFVAL	*rbf1j = &mig->rbfv[1]->rbfa[j];
-			double		rad2;
-			FVECT		v;
-			int		pos[2];
-			rad2 = R2ANG(rbf1j->crad);
-			rad2 = rad0*rad0*(1.-t) + rad2*rad2*t;
-			rbf->rbfa[n].peak = peak0 * mv * rbf->vtotal *
-						rad0*rad0/rad2;
-			rbf->rbfa[n].crad = ANG2R(sqrt(rad2));
-			ovec_from_pos(v, rbf1j->gx, rbf1j->gy);
-			geodesic(v, v0, v, t, GEOD_REL);
-			pos_from_vec(pos, v);
-			rbf->rbfa[n].gx = pos[0];
-			rbf->rbfa[n].gy = pos[1];
-			++n;
-		}
-	}
-	rbf->vtotal *= mig->rbfv[0]->vtotal;	/* turn ratio into actual */
-	return(rbf);
-memerr:
-	fprintf(stderr, "%s: Out of memory in e_advect_rbf()\n", progname);
-	exit(1);
-	return(NULL);	/* pro forma return */
-}
-
 /* Advect between recorded incident angles and allocate new RBF */
 RBFNODE *
 advect_rbf(const FVECT invec, int lobe_lim)
diff --git a/src/cv/bsdfmesh.c b/src/cv/bsdfmesh.c
index 5e2ae88e2..31be850cf 100644
--- a/src/cv/bsdfmesh.c
+++ b/src/cv/bsdfmesh.c
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: bsdfmesh.c,v 2.15 2014/02/18 16:06:51 greg Exp $";
+static const char RCSid[] = "$Id: bsdfmesh.c,v 2.16 2014/02/19 05:16:06 greg Exp $";
 #endif
 /*
  * Create BSDF advection mesh from radial basis functions.
@@ -489,10 +489,11 @@ mesh_from_edge(MIGRATION *edge)
 static void
 check_normal_incidence(void)
 {
-	const int	saved_nprocs = nprocs;
-	RBFNODE		*near_rbf, *mir_rbf, *rbf;
-	double		bestd;
-	int		n, i, j;
+	static const FVECT	norm_vec = {.0, .0, 1.};
+	const int		saved_nprocs = nprocs;
+	RBFNODE			*near_rbf, *mir_rbf, *rbf;
+	double			bestd;
+	int			n;
 
 	if (dsf_list == NULL)
 		return;				/* XXX should be error? */
@@ -542,45 +543,8 @@ check_normal_incidence(void)
 	nprocs = 1;				/* compute migration matrix */
 	if (mig_list != create_migration(mir_rbf, near_rbf))
 		exit(1);			/* XXX should never happen! */
-	n = 0;					/* count migrating particles */
-	for (i = 0; i < mtx_nrows(mig_list); i++)
-	    for (j = 0; j < mtx_ncols(mig_list); j++)
-		n += (mtx_coef(mig_list,i,j) > FTINY);
-	rbf = (RBFNODE *)malloc(sizeof(RBFNODE) + sizeof(RBFVAL)*(n-1));
-	if (rbf == NULL)
-		goto memerr;
-	rbf->next = NULL; rbf->ejl = NULL;
-	rbf->invec[0] = rbf->invec[1] = 0; rbf->invec[2] = 1.;
-	rbf->nrbf = n;
-	rbf->vtotal = .5 + .5*mig_list->rbfv[1]->vtotal/mig_list->rbfv[0]->vtotal;
-	n = 0;					/* advect RBF lobes halfway */
-	for (i = 0; i < mtx_nrows(mig_list); i++) {
-	    const RBFVAL	*rbf0i = &mig_list->rbfv[0]->rbfa[i];
-	    const float		peak0 = rbf0i->peak;
-	    const double	rad0 = R2ANG(rbf0i->crad);
-	    FVECT		v0;
-	    float		mv;
-	    ovec_from_pos(v0, rbf0i->gx, rbf0i->gy);
-	    for (j = 0; j < mtx_ncols(mig_list); j++)
-		if ((mv = mtx_coef(mig_list,i,j)) > FTINY) {
-			const RBFVAL	*rbf1j = &mig_list->rbfv[1]->rbfa[j];
-			double		rad2;
-			FVECT		v;
-			int		pos[2];
-			rad2 = R2ANG(rbf1j->crad);
-			rad2 = .5*(rad0*rad0 + rad2*rad2);
-			rbf->rbfa[n].peak = peak0 * mv * rbf->vtotal *
-						rad0*rad0/rad2;
-			rbf->rbfa[n].crad = ANG2R(sqrt(rad2));
-			ovec_from_pos(v, rbf1j->gx, rbf1j->gy);
-			geodesic(v, v0, v, .5, GEOD_REL);
-			pos_from_vec(pos, v);
-			rbf->rbfa[n].gx = pos[0];
-			rbf->rbfa[n].gy = pos[1];
-			++n;
-		}
-	}
-	rbf->vtotal *= mig_list->rbfv[0]->vtotal;
+						/* interpolate normal dist. */
+	rbf = e_advect_rbf(mig_list, norm_vec, 2*near_rbf->nrbf);
 	nprocs = saved_nprocs;			/* final clean-up */
 	free(mir_rbf);
 	free(mig_list);
diff --git a/src/cv/bsdfrep.c b/src/cv/bsdfrep.c
index fdff853d9..24b2ac803 100644
--- a/src/cv/bsdfrep.c
+++ b/src/cv/bsdfrep.c
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: bsdfrep.c,v 2.19 2013/11/09 05:47:49 greg Exp $";
+static const char RCSid[] = "$Id: bsdfrep.c,v 2.20 2014/02/19 05:16:06 greg Exp $";
 #endif
 /*
  * Support BSDF representation as radial basis functions.
@@ -393,6 +393,92 @@ get_triangles(RBFNODE *rbfv[2], const MIGRATION *mig)
 	return((rbfv[0] != NULL) + (rbfv[1] != NULL));
 }
 
+/* Advect and allocate new RBF along edge (internal call) */
+RBFNODE *
+e_advect_rbf(const MIGRATION *mig, const FVECT invec, int lobe_lim)
+{
+	double		cthresh = FTINY;
+	RBFNODE		*rbf;
+	int		n, i, j;
+	double		t, full_dist;
+						/* get relative position */
+	t = Acos(DOT(invec, mig->rbfv[0]->invec));
+	if (t < M_PI/grid_res) {		/* near first DSF */
+		n = sizeof(RBFNODE) + sizeof(RBFVAL)*(mig->rbfv[0]->nrbf-1);
+		rbf = (RBFNODE *)malloc(n);
+		if (rbf == NULL)
+			goto memerr;
+		memcpy(rbf, mig->rbfv[0], n);	/* just duplicate */
+		rbf->next = NULL; rbf->ejl = NULL;
+		return(rbf);
+	}
+	full_dist = acos(DOT(mig->rbfv[0]->invec, mig->rbfv[1]->invec));
+	if (t > full_dist-M_PI/grid_res) {	/* near second DSF */
+		n = sizeof(RBFNODE) + sizeof(RBFVAL)*(mig->rbfv[1]->nrbf-1);
+		rbf = (RBFNODE *)malloc(n);
+		if (rbf == NULL)
+			goto memerr;
+		memcpy(rbf, mig->rbfv[1], n);	/* just duplicate */
+		rbf->next = NULL; rbf->ejl = NULL;
+		return(rbf);
+	}
+	t /= full_dist;
+tryagain:
+	n = 0;					/* count migrating particles */
+	for (i = 0; i < mtx_nrows(mig); i++)
+	    for (j = 0; j < mtx_ncols(mig); j++)
+		n += (mtx_coef(mig,i,j) > cthresh);
+						/* are we over our limit? */
+	if ((lobe_lim > 0) & (n > lobe_lim)) {
+		cthresh = cthresh*2. + 10.*FTINY;
+		goto tryagain;
+	}
+#ifdef DEBUG
+	fprintf(stderr, "Input RBFs have %d, %d nodes -> output has %d\n",
+			mig->rbfv[0]->nrbf, mig->rbfv[1]->nrbf, n);
+#endif
+	rbf = (RBFNODE *)malloc(sizeof(RBFNODE) + sizeof(RBFVAL)*(n-1));
+	if (rbf == NULL)
+		goto memerr;
+	rbf->next = NULL; rbf->ejl = NULL;
+	VCOPY(rbf->invec, invec);
+	rbf->nrbf = n;
+	rbf->vtotal = 1.-t + t*mig->rbfv[1]->vtotal/mig->rbfv[0]->vtotal;
+	n = 0;					/* advect RBF lobes */
+	for (i = 0; i < mtx_nrows(mig); i++) {
+	    const RBFVAL	*rbf0i = &mig->rbfv[0]->rbfa[i];
+	    const float		peak0 = rbf0i->peak;
+	    const double	rad0 = R2ANG(rbf0i->crad);
+	    FVECT		v0;
+	    float		mv;
+	    ovec_from_pos(v0, rbf0i->gx, rbf0i->gy);
+	    for (j = 0; j < mtx_ncols(mig); j++)
+		if ((mv = mtx_coef(mig,i,j)) > cthresh) {
+			const RBFVAL	*rbf1j = &mig->rbfv[1]->rbfa[j];
+			double		rad2;
+			FVECT		v;
+			int		pos[2];
+			rad2 = R2ANG(rbf1j->crad);
+			rad2 = rad0*rad0*(1.-t) + rad2*rad2*t;
+			rbf->rbfa[n].peak = peak0 * mv * rbf->vtotal *
+						rad0*rad0/rad2;
+			rbf->rbfa[n].crad = ANG2R(sqrt(rad2));
+			ovec_from_pos(v, rbf1j->gx, rbf1j->gy);
+			geodesic(v, v0, v, t, GEOD_REL);
+			pos_from_vec(pos, v);
+			rbf->rbfa[n].gx = pos[0];
+			rbf->rbfa[n].gy = pos[1];
+			++n;
+		}
+	}
+	rbf->vtotal *= mig->rbfv[0]->vtotal;	/* turn ratio into actual */
+	return(rbf);
+memerr:
+	fprintf(stderr, "%s: Out of memory in e_advect_rbf()\n", progname);
+	exit(1);
+	return(NULL);	/* pro forma return */
+}
+
 /* Clear our BSDF representation and free memory */
 void
 clear_bsdf_rep(void)
diff --git a/src/cv/bsdfrep.h b/src/cv/bsdfrep.h
index 5aaa886c1..ec3b75e2b 100644
--- a/src/cv/bsdfrep.h
+++ b/src/cv/bsdfrep.h
@@ -1,4 +1,4 @@
-/* RCSid $Id: bsdfrep.h,v 2.11 2013/11/09 05:47:49 greg Exp $ */
+/* RCSid $Id: bsdfrep.h,v 2.12 2014/02/19 05:16:06 greg Exp $ */
 /*
  * Definitions for BSDF representation used to interpolate measured data.
  *
@@ -186,5 +186,9 @@ extern void		build_mesh(void);
 /* Find edge(s) for interpolating the given vector, applying symmetry */
 extern int		get_interp(MIGRATION *miga[3], FVECT invec);
 
+/* Advect and allocate new RBF along edge (internal call) */
+extern RBFNODE *	e_advect_rbf(const MIGRATION *mig,
+					const FVECT invec, int lobe_lim);
+
 /* Partially advect between recorded incident angles and allocate new RBF */
 extern RBFNODE *	advect_rbf(const FVECT invec, int lobe_lim);