#$%^&*AU2015203335B220190711.pdf#####ABSTRACT A probe having a contact force sensor is inserted into a cardiac chamber and an image of the blood pool is generated. A portion of the blood pool is removed from the image to retain a remaining portion of the blood pool. A determination is made that the distal segment of the probe is within the remaining portion of the blood pool, and responsively to the determination the contact force sensor is manually zeroed. 17 /n6/ 1 s 777 1n-i 1910o 14 32 33 34 18 12 30- . ;. 30 30 1420 16 2 535 ./ ,24 -25 28 35-22 38 FIG. 1