diff --git a/utils/Modeller/normalmap.cxx b/utils/Modeller/normalmap.cxx
index 78daec4ba..d6763de53 100644
--- a/utils/Modeller/normalmap.cxx
+++ b/utils/Modeller/normalmap.cxx
@@ -35,11 +35,6 @@ int parse_option(char **args, int n) {
    }
 
    sz = strlen(opt);
-   if (!strncmp(opt, "-help", sz)) {
-      printf("usage:\n  normalmap [-c=contrast] [-b=brightness]");
-      printf(" --t=file [--o=file]\n");
-      exit(0);
-   }
    if (!strncmp(opt, "-contrast", sz)) {
       contrast = atof(arg);
       return ret;
@@ -58,6 +53,11 @@ int parse_option(char **args, int n) {
       normalmap_file = strdup(arg);
       return ret;
    }
+   if (!strncmp(opt, "-help", sz)) {
+      printf("usage:\n  normalmap [-c=contrast] [-b=brightness]");
+      printf(" --i=file [--o=file]\n\n");
+      exit(0);
+   }
 
    return 1;
 }
@@ -71,7 +71,9 @@ int main (int argc, char **argv)
 
    if ( !texture_file )
    {
-      printf("Error: texture file not specified\n");
+      printf("Error: texture file not specified.\n");
+      printf("usage:\n  normalmap [-c=contrast] [-b=brightness]");
+      printf(" --i=file [--o=file]\n\n");
       return -1;
    }
 
@@ -79,7 +81,7 @@ int main (int argc, char **argv)
    if ( !texture.texture() )
    {
       printf("Error: unable to process input file: %s\n", texture_file);
-      printf("       (%s)\n", texture.err_str());
+      printf("       (%s)\n\n", texture.err_str());
       return -2;
    }
 
diff --git a/utils/Modeller/texture.cxx b/utils/Modeller/texture.cxx
index 6f744c35d..3c747e60c 100644
--- a/utils/Modeller/texture.cxx
+++ b/utils/Modeller/texture.cxx
@@ -901,6 +901,7 @@ SGTexture::make_normalmap(float brightness, float contrast) {
          int yp1 = (y < (texture_height-1)) ? y+1 : 0;
          int posxp1 = (xp1 + ytw)*num_colors;
          int posyp1 = (x + yp1*texture_width)*num_colors;
+         float fx,fy;
 
          GLubyte c = texture_data[dpos];
          GLubyte cx1 = texture_data[posxp1];
@@ -918,8 +919,11 @@ SGTexture::make_normalmap(float brightness, float contrast) {
             map[mpos+3] = a;
          }
 
-         map[mpos+0] = (128+(cx1-c)/2);
-         map[mpos+1] = (128+(cy1-c)/2);
+         fx = asin((c/256.0-cx1/256.0))/1.57079633;
+         fy = asin((cy1/256.0-c/256.0))/1.57079633;
+
+         map[mpos+0] = (GLuint)(fx*256.0)-128;
+         map[mpos+1] = (GLuint)(fy*256.0)-128;
          map[mpos+2] = 127+int(brightness*128); // 255-c/2;
 
          mpos += colors;