Indoor Takeoff with Mavros


I’m currently working with Pixhawk mini, PX4 and Mavros (ROS Melodic) to do an automatic flight.
I would like to control the drone with my computer and Mavros. The drone is conected with an FTDI cable and for the moment I can send some commands with Mavros and change the OFFBOARD mode.
I succeeded to do an outdoor takeoff with the following commands :
roslaunch mavros px4.launch fcu_url:="/dev/ttyUSB0:57600"
rosrun mavros mavsafety arm
rosrun mavros mavcmd sethome -c 0 0 0
rosrun mavros mavcmd takeoffcur 0.1 0.1 0.2 (min_pitch , yaw, altitude)
rosrun mavros mavcmd landcur 0.0 0.0 (yaw, altitude)
rosrun mavros mavsafety disarm

However, when I want to do an indoor takeoff, I need to locate the drone to set the home position but I don’t know how to do without the GPS. I saw in the PX4 website the tutorial Using Vision or Motion Capture Systems for Position Estimation but I don’t have any camera. Is there someone who faced the same problem and solved it ?
Thank you for your suggestions

For the drone to takeoff and hover in position, you need position feedback. For indoor flight, you may use the option that you already mentioed or PXFlow sensor.