Lat/Long/....AGL???

@swope
Thanks a lot for your patience and help, I did it :) , timed launch, rendezvous and dock (orbital mechanics avoided)
https://www.simplerockets.com/Videos/View/53797

@crowxe - height is just the 2norm of the position vector? Well, distance from the center of the planet...

@swope alright. I got it now, initially it confused me that non of the 3 numbers contained altitude nor radius of orbit but now I tried to use the x and z together, they returned my semi-major (my orbit is nearly perfect circle) . Oh man thank you a lot. I hope it's OK to ask you if I have other problems

@swope AGL / MSL block is only for my craft , the problem is with the target MSL , if PCI target position returns the distance from the center of planet then bingo...and I have no problem and would be no need for this post . I'll confirm and get back to you

@crowxe - there's a separate block for altitude, and you have the option of ASL or AGL. It's just not grouped with lat/lon.

PCI coordinates are centered at the middle of the planet, but they ignore the rotation of the planet and stay aligned to the stars. Your spacecrafts don't care about the rotation of the planet, either.

Sounds like what you should focus on is the target position and target velocity. I think those might also be in PCI frame, so we can probably just subtract ownship position and velocity to get the relative vectors.

@swope oh OK, well I only wanted the MSL from that conversion, that's for the vertical alignment. For lateral alignment I use the "Y" element from the position (without the conversion of Lat/long/...) . It's not exactly an a to zee rendezvous, because as I told you it's only couple of kilometers separation that I intend to cover in ~100 seconds so whatever mess I'll put into my orbit I'll revert it back before it's irreversible. Now you said something about PCI , planet coordinate inertial ? Like coordinates from the center of planet? If that's the case then wow but I think it's not, the zero point of that coordinate system seems to be somewhere else, I did tested it.

Autonomous Orbital Rendezvous Using a Coordinate-Free, Nonsingular Orbit Representation

@crowxe - my question was about how you would use latitude and longitude for rendezvous and docking. I think you'd much rather have semi-major axis, eccentricity, inclination, argument of periapsis, right ascension of the ascending node, and true anomaly. I think you can get there with planet-centered inertial (PCI) frame position and velocity, but I have a feeling the math is a bit inconvenient (ovals described by rectangles).

The latest experimental update has target position and velocity, which should make docking feasible.

@swope oh man, i read your request there, i hardly understand 5% of it, too advanced for me. i hope you get my point of Lat/Long/MSL or help me if there's a way for rendezvous using simple math (no orbital mechanics required as i have a launch system that puts the craft in orbit within 2km from the station)

@swope i don't want to use AGL for rendezvous, it's my complain here that it's AGL instead of MSL , MSL is required to know the other Dock port altitude. The other units (position using PCI) are not using the planet's center for reference as the Lat,long, AGL so it doesn't return height, it's good only for it's y axis (meters above/below the ecliptic)

There’s also something to be said about Terrain guidance radar, something a bit more up your alley. The F-111 for example employed it to stay low to the ground.

Separately, I've requested an axes-conversion block.

Why would you use lat/lon for rendezvous and docking?

The lat/lon/AGL is clearly for landing guidance.

Lat/lon/AGL is useful for landing on the surface, of course.

MSL is also useful. But isn't there a position vector in PCI?

@Bmcclory i was referring to the craft position vector when converted to Lat,long,AGL in new vizzy, it's a fixed conversion order, I wish it had a selector between AGL and MSL