Changing depth camera orientation

edit

I am using ros melodic on Ubuntu 18.04

I have a depth camera model attached to a drone , but the depth image is such that the camera is facing forward...however, it was mentioned that the depth camera is downward facing...

I have a folder called "models" which contains 2 folders: "drone_with_depth_camera" and "gimbal_small_2d".

The models.sdf file of the drone_with_depth camera looks like this(the part with the depth camera information):

model name="drone_with_depth_camera"

<include>
  <uri>model://iris_base</uri>
</include>
<include>
  <uri>model://gimbal_small_2d</uri>
  <pose>0 -0.01 0.070 1.57 0 1.57</pose>
</include>

And, the models.sdf file of the gimbal_small_2d looks like this(the part with the depth camera info):

<sensor name="depth_camera" type="depth">
        <pose>0 0 0 -1.57 -1.57 0</pose>
        <update_rate>20</update_rate>
        <always_on>1</always_on>
        <visualize>true</visualize>
        <camera>
          <horizontal_fov>1.047198</horizontal_fov>
          <image>
            <width>640</width>
            <height>480</height>
            <format>R8G8B8</format>
          </image>
          <clip>
            <near>0.1</near>
            <far>20</far>
          </clip>
        </camera>
        <plugin name="depth_controller" filename="libgazebo_ros_openni_kinect.so">
          <baseline>0.2</baseline>
          <alwaysOn>true</alwaysOn>
          <updateRate>10.0</updateRate>
          <cameraName>depth_camera</cameraName>
          <imageTopicName>/depth_camera/rgb/image_raw</imageTopicName>
          <cameraInfoTopicName>/depth_cameracamera/color/camera_info</cameraInfoTopicName>
          <depthImageTopicName>/depth_camera/depth/image_raw</depthImageTopicName>
          <depthImageInfoTopicName>/depth_cameracamera/depth/camera_info</depthImageInfoTopicName>
          <pointCloudTopicName>depth/points</pointCloudTopicName>
          <frameName>camera_link_optical</frameName>
          <pointCloudCutoff>0.4</pointCloudCutoff>
          <pointCloudCutoffMax>10.0</pointCloudCutoffMax>
          <distortionK1>0.0</distortionK1>
          <distortionK2>0.0</distortionK2>
          <distortionK3>0.0</distortionK3>
          <distortionT1>0.0</distortionT1>
          <distortionT2>0.0</distortionT2>
          <CxPrime>0</CxPrime>
          <Cx>0</Cx>
          <Cy>0</Cy>
          <focalLength>0.0</focalLength>
          <focalLength>0</focalLength>
          <hackBaseline>0</hackBaseline>
        </plugin>

      </sensor>

In rviz, I have 2 kinds of image topics:

• /depth camera/depth/image raw
• /depth camera/rgb/image raw

The rgb image is such that the camera is facing downwards, however the depth image (what I'm interested in) is such that the camera is facing horizontally....

How can I get the depth_image from the perspective of a downward facing camera instead of a forward facing one?