Yes, It is definitely possible to calculate depth with two cameras using a simple pinhole camera model:
depth = bcm*fcm/(sensorWidthCm*disparity/(float)horizontalResolution);
Here, in order to find average disparity (horizontal pixel location difference of keypoints) you can use SurfDescriptorExtractor
and to find match pairs, you can use BFMatcher
as in the link:
http://docs.opencv.org/doc/tutorials/features2d/feature_description/feature_description.html
fcm, bcm, sensorWidthCm, and horizontalResolution are all camera parameters: fcm is camera focal length, bcm is the separation of cameras, sensorWidthCm is camera sensor width, and horizontalResolution is pixel number in horizontal direction. In fact you do not separately need all these parameters. You just need to experiment with some known depth to find the ratio:bcm*fcm/sensorWidthCm
Horizontal image resolution is already known during image capture.