Connection between depth intrinsic parameters and configuration files in simulation

[xEnVrE]

While looking at the configuration files used for cameras in simulation, I noticed that the one used for the depth part, i.e.,

ergocub-software/urdf/ergoCub/robots/ergoCubGazeboV1_1/model.urdf

Lines 3479 to 3481 in 001eef3

	<plugin name="ergocub_yarp_gazebo_plugin_depthCamera" filename="libgazebo_yarp_depthCamera.so">
	<yarpConfigurationFile>model://ergoCub/conf/sensors/gazebo_ergocub_rgbd_camera.ini</yarpConfigurationFile>
	</plugin>

contains a section

ergocub-software/urdf/ergoCub/conf/sensors/gazebo_ergocub_rgbd_camera.ini

Lines 4 to 8 in 001eef3

	[CAMERA_PARAM]
	focalLengthX 389.453
	focalLengthY 389.453
	tangentialPointX 0.0
	tangentialPointY 0.0

with focal parameters.

However, if I run the robot in simulation inside Gazebo and I try to obtain the intrinsic parameters of the depth part, e.g. using rpc directly, I get the following answer:

yarp rpc /ergocubSim/depthCamera/rpc:i
visr get intp
Response: [visr] [intp] [is] ((distortionModel plumb_bob) (focalLengthX 457.02216941509868775) (focalLengthY 457.02216941509868775) (k1 0.0) (k2 0.0) (k3 0.0) (physFocalLength 0.0) (principalPointX 319.5) (principalPointY 239.5) (rectificationMatrix (1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0)) (stamp 65.9140000000000014779) (t1 0.0) (t2 0.0))

which tells that the focal lengths are $f_x = f_y = 457.02216941509868775$ that are different from those from the configuration file.

Indeed, the field of view used for the depth camera inside the urdf is:

ergocub-software/urdf/ergoCub/robots/ergoCubGazeboV1_1/model.urdf

Line 3459 in 001eef3

<horizontal_fov>1.2217</horizontal_fov>

whose corresponding focal length is:

$$ f_x = \frac{w}{ 2.0 \mathrm{tan}((\mathrm{fov}_h) / 2.0)} = 457.0221842813957 $$

with $w = 640$ the width and $\mathrm{fov}_h$ the horizontal field of view from the urdf.

Hence, it seems that the parameters from the configuration file are ignored - which I actually also like as otherwise they might differ from the field of view inside the urdf.

Is anybody aware if the parameters inside the [CAMERA_PARAM] are actually used or not? Should we remove them?

Thank you

cc @traversaro @Nicogene