When using my Vive in SteamVR Home I get lots of distortion. The tree flex as I rotate my head left to right.
You guys with your Pimaxes might just be seeing the same thing and it might have nothing to do with the Pimax lenses or distortion profiles.
When I go into a game the distortion vanishes and looks perfect.
Don’t use SteamVR home to test distortion.
It’s the same in games.
I’ve never really noticed any distortion with my Vive Pro (apart from the time when I used gearVR lenses before applying the distortion mod), the VR world always felt and looked VERY solid on that HMD. The Odyssey+ has some very slight distortion though, I think they need to tweak their profile
Updated. To 0.91 and nothing changed in terms of distortion at the edges imho, just installed and tested for a few seconds.
I did some digging and found it 
It’s stored in the pi_server.exe:
"format_ver": 2,
"name":"Pimax P2 5K Formal",
"product":"Pimax P2C",
"usb_vid":1155,
"usb_pid":257,
"default_eye_relief":0.013,
"use_tracker":"light_house",
"has_physical_ipd_adjust":true,
"support_controller_pair":true,
"need_keep_display_alive":true,
"support_hmd_standby_mode":false,
"support_hmd_bl_open_close":false,
"support_hmd_brainwarp":false,
"support_hmd_parallel_projection_led_indicator":true,
"min_firmware_version":"2.1.255.147",
"displays": [
{
"enable": true,
"edid_vid":53838,
"edid_pid":4121,
"display_scan_dir": "TB",
"v_size":0.12096,
"h_size":0.13608,
"gap":0.0037,
"pixel_settle_time":0.0,
"pixel_persist_time":0.0,
"display_shutter_type":"global"
}
],
"render":{
"double_buffer":false,
"allow_extend_mode":false,
"pixels_per_tan_angle_at_center_rate":1.25,
"lens_separation_to_ipd_rate":0.0669,
"eyes":[
{
"rotate":270,
"fov_fix_degree":10,
"lens_fix_degree":-4,
"distortion_enable":true,
"view_port": "left",
"extra_predict_time":0.009
},
{
"rotate":90,
"fov_fix_degree":-10,
"lens_fix_degree":4,
"distortion_enable":true,
"view_port": "right",
"extra_predict_time":0.154
}
],
"fov":{
"default_fov_level":1,
"extra":[1,1],
"extra_fix":[6,6]
},
"hidden_area":{
"enable":true,
"triangle_split_to":10,
"triangles-custom-fov":[
0.4,0.0, 0.0,0.0, 0.0,0.4,
0.0,0.6, 0.0,1.0, 0.4,1.0,
1.0,0.2, 1.0,0.0, 0.8,0.0,
0.8,1.0, 1.0,1.0, 1.0,0.8
],
"triangles_fix-custom-fov":[
0.4,0.0, 0.0,0.0, 0.0,0.4,
0.0,0.6, 0.0,1.0, 0.4,1.0,
1.0,0.2, 1.0,0.0, 0.8,0.0,
0.8,1.0, 1.0,1.0, 1.0,0.8
],
"triangles":[
0.2,0.0, 0.0,0.0, 0.0,0.2,
0.0,0.8, 0.0,1.0, 0.2,1.0,
1.0,0.2, 1.0,0.0, 0.8,0.0,
0.8,1.0, 1.0,1.0, 1.0,0.8
],
"triangles_fix":[
1.0,0.2, 1.0,0.0, 0.8,0.0,
0.8,1.0, 1.0,1.0, 1.0,0.8
]
}
},
"lens":{
"separation":0.100,
"adc_to_separation_K":[4960.0,-0.168],
"diameter":0.072,
"inner_diameter":0.035,
"MetersPerTanAngleAtCenter":0.03919542,
"v_center_off":0,
"distortion_param":
{
"eqn": "CatmullRom17",
"K":[1.0000,1.0484,1.1042,1.1800,1.2650,1.3450,1.4200,1.4700,1.4900,1.5000,1.5100,1.5100,1.5200,1.5400,1.5670,1.5900,1.6100,1.6260 ],
"ChromaticAberration":[-0.005,-0.007,0.008,0.023],
"MaxRadius": 1.4757009417836655,
"EyeRelief": 0.018
}
}
}
See the “lens” part. The distortion seems to be specified by 17 ‘spline points’ as per ‘CatmullRom17’. You can google "Catmullrom10’ for some info on the 10 points version (I guess for regular FoV hmds)
Haven’t tried messing with the params yet, will try later, but if you want to try yourself please keep in mind that the pi_server.exe contains various of these config files for different HMD’s, you need to edit that “Pimax P2 5K Formal” for the 5k+ version.
Success 
I’ve changed some of that “K” values and in the pi_server.exe file (in that specific table for the 5k), rebooted the pc and now distortion is REALLY messed up, LOL. So it works, we can now change distortion ourselves !!
good luck winging a distortion profile lol
Awesome find! well played
Now we just do what pimax did and run a RNG on it 
I think it may be more complicated than that. The distortion is probably non-linear. You’d probably need a setup like my old rear-projection TV: A grid of points, where each intersection can be adjusted (spacially) individually.
Wow, that looks “tweaky”.
The file seems comprehensive. I see separate data for color channels, so this profile can be used to pre-distort the RBG mesh, to correct chromatic aberration.
Anyone want to try changing that to “true” and giving it a test? Of course, this is at your own risk. 
I’m just busy enjoying my headset after changing…
“brightness_level:5” to “brightness_level:8”
(made you look!)
I just tried large FOV and rebooted steamVR and pitool (required or you get weird distortion when in app) and I feel like it looks really good and a lot better on 0.91. So good that I may just use large fov from now on. Is anyone else seeing this too or is it also in my head?
Please do a reboot of pitool and steamvr after changing it to large then start your app.
Edit: Also I would love to tweak those distortion profiles, and brightness settings but I’m afriad. How do I make a backup first? Any way you could write really clear step by step instructions @Sjef or @spamenigma (also this info deserves it’s own post)
Update: Showed fiancee large fov, coke bottle effect is still there she said… she said normal fov is better Seems it’s all in my head and I am just immune now
@spamenigma This could turn out like those vorpx cloud profiles and could be a bad thing. Whenever I would try someone elses vorpx profile or fov settings it was aweful, this definitely shouldn’t be something people just eyeball… but using like a grid of points like neal said. Using other people’s vr profiles at least in vorpx with fov and various tweaks can be very bad, but some profiles there are decent. This kind of profile tweaking sort of feels like that in a way, so giving that example.
Back in the day I used to converge the old 3 gun CRT projectors after they were installed, NEC brand.
First I would physically adjust the yokes on each crt gun, red, green, blue, to converge all colors to line up as best as possible with a test pattern, usually a grid of a sort. Then I would go into the electrical settings and converge a small quadrant of the screen at a time to compensate for each individual crt distortion , much like the rear projection TV’s .
It would be great if an updated software could take care of the distortions but if the distortions are specific to each HMD, that might be hard?? So if we as Pimax users could individually “converge” each of our own HMD’s, that might be beneficial.
I only ever adjusted the settings using the remote.
The Mitsubishi set still runs, but it’s way out of adjustment and I haven’t bothered to go through the calibration process again.
Somebody sees the distortion. Somebody does not see it. Philosophically if you don’t see it, it does not exist, and vice versa. I see the distortion from the very beginning, and I also feel the distortion getting smaller with later Pitools. I don’t know if it’s real improvement, or just placebo, or both. What I am sure is that now I don’t notice the distortion, and it does not bother me at all.
@yanfeng yes there is no spoon. “And then you’ll see that it is not the spoon that bends, it is only the edge distortion from the lenses.” -matrix kid
Yes please, for science
huh ? you really changed brightness ?
(202020 202020 202020)