Before displaying satellite data, you must know the ADDE dataset name under which it is stored. The DSINFO and IMGLIST commands can list information about image datasets you have access to. Once located, you can display the images using the IMGDISP command.

When you display an image on a frame, McIDAS creates a frame directory for the image which lists the frame number, sensor source, date, image time, band number, image coordinates, magnification factors, and ADDE dataset name and file position number. The FRMLIST command lists the frame directory.

You can display images one at a time or in a sequence. If the areas on disk are chronologically ordered, an entire set of images can be sequentially loaded using one IMGDISP command with a repeat factor.

In this exercise, you will select two images and display them on frames, list the frame directory for one frame, and display a sequence of images using the IMGDISP command with a repeat factor.

1. Start a McIDAS session.

   At the Unix prompt:

   Type: mcidas

   Your session should still be set for six frames from the last time you edited your .mcidasrc file. If not, set it for six frames, as described in Getting Started.

2. Log on and initialize the workstation.

   Type: LOGON   initials   project#   I

3. List the area directories for the first 3 images in the BLIZZARD/G7-VIS-4K dataset.

   Type: IMGLIST BLIZZARD/G7-VIS-4K.1 3

   Image file directory listing for:BLIZZARD/G7-VIS-4K                    
    Pos Satellite/         Date       Time      Center   Band(s)          
        sensor                                 Lat  Lon                   
    --- -------------  ------------  --------  ---- ---- ------------     
      1  GOES-7        13 MAR 93072  17:01:00    26   87 1                
      2  GOES-7        13 MAR 93072  17:31:00    26   87 1                
      3  GOES-7        13 MAR 93072  18:01:00    26   87 1                
   

4. List the area directories of the first 3 images of the BLIZZARD/G7-VIS-4K dataset that contain images taken at 17:01:00 UTC on day 93072.

   Type: IMGLIST BLIZZARD/G7-VIS-4K.1 3 DAY=93072 TIME=17:01:00

   Image file directory listing for:BLIZZARD/G7-VIS-4K                    
    Pos Satellite/         Date       Time      Center   Band(s)          
        sensor                                 Lat  Lon                   
    --- -------------  ------------  --------  ---- ---- ------------     
      1  GOES-7        13 MAR 93072  17:01:00    26   87 1                
   

5. Display the first GOES-7 visible 4km image on frame 1. Use the alias that you created in the ADDE - Getting Started section as the dataset name.

   Type: IMGDISP GV4.1 1

   Notice that the bottom of the image has an annotation line which lists the frame number, satellite type, sensor source, Gregorian date, Julian date, UTC time, upper-left corner image line and element, and resolution. For a GOES-7 visible image, the sensor source is blank.

6. Display the first GOES-7 4km IR image on frame 4 and show frame 4.

   Type: IMGDISP GI4.1 4

   Press: Alt O

   Notice that Alt O is an easy way to compare visible and infrared images displayed on opposite frames.

7. List the frame directory for the current image on frame 4.

   Type: FRMLIST

   Information about the frame number, sensor source, band, date, time, and ADDE dataset/position number is displayed for the image.

   FRMLIST                                                                              
     Frame   Satellite                                                                  
    [panel]  Sensor       Band     Date       Time   Data Source                        
   --------- ------------ ---- ------------ -------- -----------------------------      
        4[1] GOES-7 IR     8   13 Mar 93072 17:01:00 GI4.1                              
   FRMLIST: Done   

8. Display three areas that are in sequence using one IMGDISP command.

   Type: IMGDISP BLIZZARD/M3-VIS.1 4 REPEAT=3

   The repeat factor is 3; therefore this entry displays three images in sequence, on frames 4, 5, and 6.

9. Step through the frames to view the images.

   Press: Alt A

   Press: Alt B

10. Erase the contents of frames 4 through 6 to prepare for the next exercise.

    Type: ERASE I 4 6