Ripping the ISO from the Gamecube disc, Not the Phantasy Star method

I want to rip some things from a gamecube disc, and I have the tools to use with the ISO once I rip it, but I don't know how to get the actual ISO off of the disc. I have an official SSBM disk. I don't want to use the Phantasy Star Method, I just want to get the ISO off the disc. But whenever I put the disk in my computer's drive, it says it has no storage space and nothing on it. Can anybody help with this?

You can't access it directly...!

Well, you're trying to get the wrong format of data from the disk. Gamecube disks do NOT use the ISO standard. Instead they use the GCM (GameCube Media) format. It is a format your DVD-ROM drive will not be able to understand.

You have to use either the PSO method or another, more modern method to dump GCMs from Gamecube games. Newer methods use the Action Replay and SD card adapters for the Gamecube memory slot.

Oh.

pretty much this.
first of all, terminology: I believe GCM stands for Gamecube Master, as in the "master tape" for the game itself. that's what I've seen used internally at nintendo.
second of all, it's not just the filesystem used; the optical media itself is encrypted. a Gamecube Optical Disc (GOD) is similar to a 8cm DVD, with the exception that some (cryptographically insecure, but that's not so relevant here) cryptography is used to render the data useless, and a non-standard sector format that's incompatible with UDF is used to obscure the data from most standard optical drives.
without low-level access to the drive hardware to account for these things, the easiest way to get to the data on these discs is to simply use the Gamecube's optical drive itself, by sending a small program to read the disc and send it to your computer over the network.