1. A processing system for multiple touch input object force estimation, comprising: sensor circuitry configured to acquire a plurality of touch force measurements of a sensing region on a surface using a plurality of sensor electrodes, wherein the surface is characterized by a bending response model representative of a distribution of non-uniform bending coefficients; processing circuitry connected to the sensor circuitry and configured to: obtain a delta image of the sensing region using the plurality of touch force measurements; identify a plurality of touch locations of a plurality of touch input objects in the sensing region using the delta image; identify a plurality of flattened model force images using the plurality of touch locations of the plurality of touch input objects, wherein each flattened model force image of the plurality of flattened model force images is a one-dimensional vector corresponding to a respective two-dimensional calibration information for a respective input object, and the two-dimensional calibration information comprises calibration data for a respective individual location on the surface according to the bending response model; determine a location-based force estimate for each input object of the plurality of input objects by performing a linear solve using a one-dimensional vector obtained from the delta image and the plurality of flattened model force images corresponding to the plurality of touch input objects; and perform an action based on the force estimate of each input object of the plurality of input objects.