octomap maps objects of the XY plane into the Z plane

edit

I'm trying to make a map out of a square boundary using Octomap. I am on ros kinetic and using Kinect in this process. The image data received from the camera is accurate thus, I think the camera orientation is right and not facing upwards.

However, when I tried to map the environment and put it on RViz using marker array, the four sides of the sure boundary (Turtlebot3 Plaza for reference), are mapped and meshed together upwards in the Z direction. I'm attaching the Imgur files here: http://imgur.com/gallery/S9HQVuB , as I can't post a snapshot yet.

the plugin file:

 <gazebo reference="kinect_link">
      <sensor name="kinect_link_camera" type="depth">
        <update_rate>20</update_rate>
        <camera>
          <horizontal_fov>1.047198</horizontal_fov>
          <image>
            <width>640</width>
            <height>480</height>
            <format>R8G8B8</format>
          </image>
          <clip>
            <near>0.05</near>
            <far>3</far>
          </clip>
        </camera>
        <plugin name="kinect_link_controller" filename="libgazebo_ros_openni_kinect.so">
          <baseline>0.2</baseline>
          <alwaysOn>true</alwaysOn>
          <updateRate>1.0</updateRate>
          <cameraName>${camera_name}_ir</cameraName>
          <imageTopicName>/color/image_raw</imageTopicName>
          <cameraInfoTopicName>/color/camera_info</cameraInfoTopicName>
          <depthImageTopicName>/depth/image_raw</depthImageTopicName>
          <depthImageInfoTopicName>/depth/camera_info</depthImageInfoTopicName>
          <pointCloudTopicName>/depth/points</pointCloudTopicName>
          <frameName>kinect_link</frameName>
          <pointCloudCutoff>0.5</pointCloudCutoff>
          <pointCloudCutoffMax>3.0</pointCloudCutoffMax>
          <distortionK1>0.00000001</distortionK1>
          <distortionK2>0.00000001</distortionK2>
          <distortionK3>0.00000001</distortionK3>
          <distortionT1>0.00000001</distortionT1>
          <distortionT2>0.00000001</distortionT2>
          <CxPrime>0</CxPrime>
          <Cx>0</Cx>
          <Cy>0</Cy>
          <focalLength>0</focalLength>
          <hackBaseline>0</hackBaseline>
        </plugin>
      </sensor>
    </gazebo>