diff --git a/Fonderie/sfx.c b/Fonderie/sfx.c
index 00b601a..6cb0867 100644
--- a/Fonderie/sfx.c
+++ b/Fonderie/sfx.c
@@ -129,16 +129,31 @@ float		vals[3];
 fprintf(stderr, ">>> %s ( %p %d )\n", __func__, pimg, notused);
 #endif
 
-#define STP  16			/* stepd for x & y axex */
+/*	    XXX  CRITICAL BUG  XXX
+ *
+ *	what to do if STP is not a modulo of
+ *	the width (or size) of the picture ?
+ *	why if img height is 600 and stp was 16 ?
+
+     tth@redlady:~/Devel/FloatImg/Fonderie$ bc -l
+     600/16
+     37.50000000000000000000
+
+ *
+ *   And this mistake is all around the code /o\
+ *
+ */
+#define STP  8			/* stepd for x & y axex */
 coo[2] = coo[3] = STP;
 
-for (y=0; y<pimg->height; y+=STP) {
+for (y=0; y < pimg->height; y+=STP) {
 	coo[1] = y;
-	for (x=0; x<pimg->width; x+=STP) {
+	for (x=0; x < pimg->width; x+=STP) {
 		coo[0] = x;
 		foo = stat_zone(pimg, coo, vals);
 		if (foo)	abort();
 		/* next step : plot the datas */
+		// XXX fprintf(stderr, "%s    %6d    %6d\n", __func__, x, y);
 		pixel_trinitron(pimg, coo, vals);
 		}
 	}
diff --git a/experiment/Makefile b/experiment/Makefile
index ff6a6a6..1f435ff 100644
--- a/experiment/Makefile
+++ b/experiment/Makefile
@@ -23,6 +23,12 @@ muxplanes:	muxplanes.c ${DEPS}
 movepixels:	movepixels.c ${DEPS}
 	gcc $(COPT) $<  ../libfloatimg.a ${LIBS} -o $@
 
+mnt:		mnt.c ${DEPS}
+	gcc $(COPT) $<  ../libfloatimg.a ${LIBS} -o $@
+
+fimg2obj:	fimg2obj.c $(DEPS)
+	gcc $(COPT) $<  ../libfloatimg.a ${LIBS} -o $@
+
 # ---------------------------------------------------------
 #			CACHE ENGINE
 
diff --git a/experiment/README.md b/experiment/README.md
index 789c40d..089c4f9 100644
--- a/experiment/README.md
+++ b/experiment/README.md
@@ -9,4 +9,13 @@ Le contenu de ce répertoire doit donc être considéré comme
 **volatile**. Si vous y trouvez votre bonheur, il serait sage
 d'en faire une copie personnelle...
 
+## MNT
+
+Modèles numériques de terrain. Rien ne marche.
+
+## fimg2obj
+
+Création d'un fichier .OBG (de Wavefront) à partir d'une image
+flottante afin d'avoir des vues en 3d pertinentes, bien qu'assez
+futiles.
 
diff --git a/experiment/fimg2obj.c b/experiment/fimg2obj.c
new file mode 100644
index 0000000..eeac4a0
--- /dev/null
+++ b/experiment/fimg2obj.c
@@ -0,0 +1,67 @@
+
+/*
+ *		another ugly experiment
+ */
+#include  <stdio.h>
+#include  <stdlib.h>
+#include  <unistd.h>
+#include  <stdint.h>
+
+#include  "../floatimg.h"
+
+int		verbosity;
+
+/* ---------------------------------------------- ~~~~~~~~~~~~~~~~ */
+
+int convert_fimg_to_obj(char *fimgfname, char *objfname, int mode)
+{
+FloatImg	src;
+int		foo, x, y;
+FILE		*fp;
+
+#if DEBUG_LEVEL
+fprintf(stderr, ">>> %s ( '%s'  '%s'  %d )\n", __func__,
+			fimgfname, objfname, mode);
+#endif
+
+if (mode) {
+	fprintf(stderr, "in %s(), mode must be 0, was %d\n", __func__, mode);
+	}
+
+foo = fimg_create_from_dump(fimgfname, &src);
+if (foo) {
+	fprintf(stderr, "err %d loading %f\n", foo, fimgfname);
+	return foo;
+	}
+
+
+	
+return -1;
+}
+/* ---------------------------------------------- ~~~~~~~~~~~~~~~~ */
+
+int main(int argc, char *argv[])
+{
+int		foo, opt;
+char		*infile  = "foo.fimg";
+
+fprintf(stderr, "*** fimg2obj   (%s %s)\n", __DATE__, __TIME__);
+
+verbosity = 0;
+
+#if 0
+for (foo=0; foo<argc; foo++) {
+	fprintf(stderr, "%9d   %s\n", foo, argv[foo]);
+	}
+#endif
+
+foo = convert_fimg_to_obj(infile, "foo.obj", 0);
+if (foo) {
+	fprintf(stderr, "convertor give us %d\n", foo);
+	exit(1);
+	}
+
+return 0;
+}
+
+/* ---------------------------------------------- ~~~~~~~~~~~~~~~~ */
diff --git a/experiment/mnt.c b/experiment/mnt.c
new file mode 100644
index 0000000..304110f
--- /dev/null
+++ b/experiment/mnt.c
@@ -0,0 +1,100 @@
+/*
+ *	Modeles Numeriques de Terrain
+ *
+ */
+
+#include   <stdio.h>
+#include   <math.h>
+#include   <stdlib.h>
+#include   <stdint.h>
+
+#include   "../floatimg.h"
+
+int		verbosity;
+
+/* ------------------------------------------------------------------- */
+/*
+ *		First try
+ */
+int brotche_mnt_style(FloatImg *src, FloatImg *dst)
+{
+int		x, y;
+int		offset;
+float		z1, z2, z3, z4;
+float		a, b, c;
+float		pente;
+
+fprintf(stderr, ">>> %s ( %p %p )\n", __func__, src, dst);
+
+#define W    (src->width)
+#define DX   1.0
+#define DY   1.0
+
+for (y=0; y<(src->height-1); y++) {
+	for (x=0; x<(src->width-1); x++) {
+		offset = (y * src->width) + x;
+		z1 = src->R[offset];
+		z2 = src->R[offset+1];
+		z3 = src->R[offset+W];
+		z4 = src->R[offset+W+1];
+
+		a = ( z1 + z2 + z3 + z4) / 4.0;
+		b = (-z1 + z2 - z3 + z4) / 2.0 / DX;
+		c = (-z1 - z2 + z3 + z4) / 2.0 / DY;
+
+		pente = atanf(sqrt(b*b + c*c));
+
+		dst->R[offset] = 0;
+		if (pente < 0.0) dst->G[offset] = pente;
+		else		 dst->B[offset] = pente;
+
+
+		}
+	}
+
+return 0;
+}
+/* ------------------------------------------------------------------- */
+int main(int argc, char *argv[])
+{
+FloatImg	src, dst;
+char		*infile, *outfile;
+int		foo;
+
+if (3 != argc) {
+	fprintf(stderr, "%s need 2 args : infile & outfile\n", argv[0]);
+	fimg_print_version(0);
+	exit(1);
+	}
+
+infile = argv[1];	outfile = argv[2];
+
+fprintf(stderr,"--- working on %s\n", infile);
+
+foo = fimg_create_from_dump(infile, &src);
+if (foo) {
+	fprintf(stderr, "err %d loading image '%s'\n", foo, infile);
+	exit(1);
+	}
+
+foo = fimg_clone(&src, &dst, 0);
+if (foo) {
+	fprintf(stderr, "err %d cloning image\n", foo);
+	exit(1);
+	}
+
+foo = brotche_mnt_style(&src, &dst);
+if (foo) {
+	fprintf(stderr, "something weird happen %d\n", foo);
+	exit(1);
+	}
+
+foo = fimg_export_picture(&dst, outfile, 0);
+if (foo) {
+	fprintf(stderr, "err %d exporting to %s\n", foo, outfile);
+	exit(1);
+	}
+
+return 0;
+}
+/* ------------------------------------------------------------------- */
diff --git a/floatimg.h b/floatimg.h
index d4a8013..72d6373 100644
--- a/floatimg.h
+++ b/floatimg.h
@@ -20,7 +20,7 @@
  *	https://git.tetalab.org/tTh/FloatImg
  */
 
-#define		FIMG_VERSION	(220)
+#define		FIMG_VERSION	(221)
 #define		RELEASE_NAME	("noname")
 
 /* XXX add a test for stdint.h / uint32_t XXX */