Index: /trunk/Ohana/src/opihi/dvo/Makefile
===================================================================
--- /trunk/Ohana/src/opihi/dvo/Makefile	(revision 4700)
+++ /trunk/Ohana/src/opihi/dvo/Makefile	(revision 4701)
@@ -80,4 +80,5 @@
 $(SDIR)/pmeasure.$(ARCH).o	  	\
 $(SDIR)/procks.$(ARCH).o	  	\
+$(SDIR)/skycoverage.$(ARCH).o	  	\
 $(SDIR)/showtile.$(ARCH).o	  	\
 $(SDIR)/simage.$(ARCH).o	  	\
Index: /trunk/Ohana/src/opihi/dvo/init.c
===================================================================
--- /trunk/Ohana/src/opihi/dvo/init.c	(revision 4700)
+++ /trunk/Ohana/src/opihi/dvo/init.c	(revision 4701)
@@ -43,4 +43,5 @@
 int procks	    PROTO((int, char **));
 int showtile	    PROTO((int, char **));
+int skycoverage	    PROTO((int, char **));
 int simage	    PROTO((int, char **));
 int subpix	    PROTO((int, char **));
@@ -93,4 +94,5 @@
   {"procks",      procks,       "plot rocks"},
   {"showtile",    showtile,     "plot tile pattern"},
+  {"skycoverage", skycoverage,  "measure image union on sky"},
   {"simage",      simage,       "plot stars in an image"},
   {"subpix",      subpix,       "get subpixel positions"},
Index: /trunk/Ohana/src/opihi/dvo/skycoverage.c
===================================================================
--- /trunk/Ohana/src/opihi/dvo/skycoverage.c	(revision 4701)
+++ /trunk/Ohana/src/opihi/dvo/skycoverage.c	(revision 4701)
@@ -0,0 +1,157 @@
+# include "dvo1.h"
+
+int skycoverage (int argc, char **argv) {
+
+  int i, N, Nimage, status, TimeSelect, ByName, xs, ys;
+  time_t tzero, tend;
+  double pixscale, dPix, r, d, Xi, Yi, Xs, Ys, x[2], y[2], trange;
+  Image *image;
+  char name[256];
+  float *V;
+  int Nx, Ny;
+  Buffer *buf;
+  Coords coords;
+
+  ByName = FALSE;
+  if ((N = get_argument (argc, argv, "-name"))) {
+    remove_argument (N, &argc, argv);
+    strcpy (name, argv[N]);
+    remove_argument (N, &argc, argv);
+    ByName = TRUE;
+  }
+
+  TimeSelect = FALSE;
+  if ((N = get_argument (argc, argv, "-time"))) {
+    remove_argument (N, &argc, argv);
+    if (!str_to_time (argv[N], &tzero)) { 
+      fprintf (stderr, "syntax error\n");
+      return (FALSE);
+    }
+    remove_argument (N, &argc, argv);
+    if (!str_to_dtime (argv[N], &trange)) { 
+      fprintf (stderr, "syntax error\n");
+      return (FALSE);
+    }
+    remove_argument (N, &argc, argv);
+    if (trange < 0) {
+      trange = fabs (trange);
+      tzero -= trange;
+    }
+    TimeSelect = TRUE;
+  }
+  if ((N = get_argument (argc, argv, "-trange"))) {
+    remove_argument (N, &argc, argv);
+    if (!str_to_time (argv[N], &tzero)) { 
+      fprintf (stderr, "syntax error\n");
+      return (FALSE);
+    }
+    remove_argument (N, &argc, argv);
+    if (!str_to_time (argv[N], &tend)) { 
+      fprintf (stderr, "syntax error\n");
+      return (FALSE);
+    }
+    remove_argument (N, &argc, argv);
+    trange = tend - tzero;
+    if (trange < 0) {
+      trange = fabs (trange);
+      tzero -= trange;
+    }
+    TimeSelect = TRUE;
+  }
+ 
+  if (argc != 4) {
+    fprintf (stderr, "USAGE: skycoverage (buffer) (pixscale) (dPix) [-time start range] [-name name]\n");
+    fprintf (stderr, "       (buffer) saves bitmapped AIT plot\n");
+    fprintf (stderr, "       (pixscale) specifies the pixel size in degrees\n");
+    fprintf (stderr, "       note: we need 64800 / (pixscale)^2 pixels to represent the sky\n");
+    return (FALSE);
+  }
+  
+  if ((buf = SelectBuffer (argv[1], ANYBUFFER, TRUE)) == NULL) return (FALSE);
+  pixscale = atof(argv[2]);
+  dPix     = atof(argv[3]);
+
+  Nx = 360/pixscale;
+  Ny = 180/pixscale;
+
+  buf[0].matrix.Naxis[0] = Nx;
+  buf[0].matrix.Naxis[1] = Ny;
+
+  /* I should encapsulate this in a create_default_buffer */
+  fits_free_matrix (&buf[0].matrix);
+  fits_free_header (&buf[0].header);
+  buf[0].header.bitpix = buf[0].bitpix = -32;
+  buf[0].header.unsign = buf[0].unsign = FALSE;
+  buf[0].header.bscale = buf[0].bscale = 1.0;
+  buf[0].header.bzero  = buf[0].bzero  = 0.0;
+  buf[0].header.Naxes = 2;
+  buf[0].header.Naxis[0] = Nx;
+  buf[0].header.Naxis[1] = Ny;
+  fits_create_header (&buf[0].header);
+  fits_create_matrix (&buf[0].header, &buf[0].matrix);
+
+  coords.crval1 = 180;
+  coords.crval2 = 0;
+  coords.crpix1 = 0.5*Nx;
+  coords.crpix2 = 0.5*Ny;
+  strcpy (coords.ctype, "DEC--AIT");
+  coords.pc1_1 = coords.pc2_2 = 1;
+  coords.pc1_2 = coords.pc2_1 = 0;
+  coords.cdelt1 = coords.cdelt2 = pixscale;
+  coords.Npolyterms = 0;
+
+  PutCoords (&coords, &buf[0].header);
+
+  if ((image = LoadImages (&Nimage)) == NULL) return (FALSE);
+  BuildChipMatch (image, Nimage);
+
+  V = (float *)buf[0].matrix.buffer;
+  bzero (V, Nx*Ny*sizeof(float));
+
+  for (ys = 0; ys < Ny; ys++) {
+    for (xs = 0; xs < Nx; xs++) {
+      status = XY_to_RD (&r, &d, (double)(xs), (double)(ys), &coords);
+      status &= (r > 0);
+      status &= (r < 360);
+      if (status) {
+	V[ys*Nx + xs] = 2;
+      }
+    }
+  }
+
+  for (i = 0; i < Nimage; i++) {
+    if (ByName && strcmp (name, image[i].name)) continue;
+    if (TimeSelect && ((image[i].tzero < tzero) || (image[i].tzero+image[i].trate*image[i].NY > tzero + trange))) continue;
+    if (!FindMosaicForImage (image, Nimage, i)) continue;
+
+    /* project this image to screen display coords */
+    /* DIS images represent a field, not a chip */
+    if (!strcmp(&image[i].coords.ctype[4], "-DIS")) {
+      x[0] = -0.5*image[i].NX; y[0] = -0.5*image[i].NY;
+      x[1] = +0.5*image[i].NX; y[1] = +0.5*image[i].NY;
+    } else {
+      x[0] = 0;                y[0] = 0;
+      x[1] = image[i].NX;      y[1] = image[i].NY;
+    }
+    status = FALSE;
+    
+    for (Yi = y[0] + 0.5*dPix; Yi < y[1]; Yi += dPix) {
+      for (Xi = x[0] + 0.5*dPix; Xi < x[1]; Xi += dPix) {
+	XY_to_RD (&r, &d, Xi, Yi, &image[i].coords);
+	while (r <   0.0) { r += 360.0; }
+	while (r > 360.0) { r -= 360.0; }
+	status = RD_to_XY (&Xs, &Ys, r, d, &coords);
+	if (status) {
+	  xs = (int)Xs;
+	  ys = (int)Ys;
+	  V[ys*Nx + xs] = 1;
+	}
+      }
+    }
+  }
+
+  free (image);
+  return (TRUE);
+}
+
+