i have tried plotting to a jpg file and it worked. instead of
importing a file using the import map command, the calibrate map
option works well when dealing with jpg and other types of images.

thanks for the suggestions guys. im still trying to evalutaing the
accuracy though. having more than 3 reference points is good in making
sure that the map is oriented properly and there are less distortions
in scale.

by the way, what will i put in the scale option during the first part
of the calibration?