Ultra high settings
From TF2 Wiki
Ultra high setting are the "hidden" graphic settings. With typing these commands in the console the game is even better looking than the very high settings. It should be noted however, that enabling all these settings can cause heavy GPU and CPU usage. Additionally, not all settings are available without setting sv_cheats. The use of these settings are suited to screenshots and machinima.
mat_picmip was the most well known and had one of the biggest visual "gains" from using. mat_picmip changed the compression of the textures used in game. mat_picmip # (numbers went from -10 to 4, -10 being the best quality and 4 being the worst.)
An example of a comparison taken from the topic in the TF2 forum where you can find more information (see below):
It should be noted, however, that this was broken in the June 10, 2010 Patch, which only allows texture setting from the default options menu. It was intentionally disabled by Valve, and now can only go to -1.
mp_usehwmmodels and mp_usehwmvcds
Setting mp_usehwmmodels and mp_usehwmvcds to "1" enables the high polygon versions of the player models, as seen in the "Meet the" videos. This makes player models more detailed, and gives them more realistic facial expressions. However, it does not work for the Pyro.
Setting this command to "1" enables flaming gibs.
If set to "1", this uses the Source Engine's updated, threaded particle system (as opposed to the original engine's system) to render bullet impact effects. The results are most noticeable on glass.
By default (r_lod "-1"), the game lowers the level of detail on objects at a distance from the camera, to save on framerate. Setting r_lod to "0" disables this, forcing the game to always display the highest detail version of each model.
Below is a comparison of the standard settings and the high settings. High settings picture also has 16xAA enabled, whereas the standard has none.
Ultra high settings config file example
cl_burninggibs 1 cl_detaildist 2400 cl_detailfade 0 cl_maxrenderable_dist 6000 cl_new_impact_effects 1 cl_ragdoll_collide 1 cl_smooth 1 cl_threaded_bone_setup 1 cl_threaded_client_leaf_system 1 dsp_enhance_stereo 1 lod_TransitionDist 6400 mat_aaquality 8 mat_antialiasing 16 mat_antialinis 16 mat_bumpmap 1 mat_clipz 0 mat_hdr_tonemapscale 16 mat_motion_blur_forward_enabled 1 mat_picmip -1 mat_queue_mode 2 mat_specular 1 mp_usehwmmodels 1 mp_usehwmvcds 1 r_fastzreject 1 r_lod 0 r_threaded_client_shadow_manager 1 r_threaded_particles 1 r_threaded_renderables 1 r_waterforceexpensive 1 snd_mixahead 1 echo Custom config loaded