Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 07-27-2019, 04:26 AM   #1
scc
 
Join Date: Mar 2013
Default Inertial Guidance, What Is It? (In GURPS Terms)

OK, for those who don't know, inertial guidance is the science behind knowing where you are by keeping careful track of how far you move, and involves one or more accelerometers and a chronometer. Orienteering courses in scouts and being able to find your way around in a place blind folded are actually fairly similar.

I want to know what this ability would be in terms of Advantages. At first I thought it simply be Absolute Direction with a limitation, but as I've realized recently that having it allows you to build a map of where you've been in some unknown place, that can't be right, so anyone got any ideas or have I stumbled upon something we somehow don't have yet?
scc is offline   Reply With Quote
Old 07-27-2019, 05:18 AM   #2
Daigoro
 
Daigoro's Avatar
 
Join Date: Dec 2006
Location: Meifumado
Default Re: Inertial Guidance, What Is It? (In GURPS Terms)

Maybe add Accessory (Map) to Absolute Direction?
__________________
Collaborative Settings:
Cyberpunk: Duopoly Nation
Space Opera: Behind the King's Eclipse
And heaps of forum collabs, 30+ and counting!
Daigoro is offline   Reply With Quote
Old 07-27-2019, 05:24 AM   #3
Celjabba
 
Join Date: Sep 2006
Location: Luxembourg
Default Re: Inertial Guidance, What Is It? (In GURPS Terms)

As an ability, I would have said simply a perk giving +2 or +3 to navigation rolls.
And absolute timing, if you can access the clock independently.

A suitably limited absolute direction should work, too, I think.
What exactly is the problem with maps ? Not sure I understand what you mean there. Is AD too good, or not good enough ?

You can find them as gear in Ultra-tech pg 74-75, as well as G:Traveller IW, Gurps Inf worlds, and various pyramid issues.

Last edited by Celjabba; 07-27-2019 at 05:31 AM.
Celjabba is offline   Reply With Quote
Old 07-27-2019, 05:46 AM   #4
Anaraxes
 
Join Date: Sep 2007
Default Re: Inertial Guidance, What Is It? (In GURPS Terms)

Actually, you'd need an Enhancement to Absolute Direction to match INS. Per the text, AD lets you know which way is north, and gives bonuses to a few skill rolls. INS doesn't tell you which way is north. (Smartphones and the like include a magnetometer and sense magnetic fields just like a compass -- except they also usually have a map of magnetic declination and GPS coordinates to correct that direction.)

On the other hand, knowing which direction is north doesn't tell you anything about your position. The point of INS is to have a way to know your position, not facing. INS just integrates accelerations to get change in position. But to change an acceleration from "left/right" to "east/west", the INS does need to know its facing. Sensing rotation is theoretically possible (including a gyroscope is another thing smartphones do), or you could use that compass -- which would mean an INS does everything Absolute Direction does, plus gives you position information.

I'm not sure that's worth a lot more than AD as described in the text, so you could just throw +5 points onto the cost, rather than try to come up with percentage Enhancements. Though AD may be intended to include "location" and not just "direction" in the first place, even though it doesn't actually say so.

As a special case, teleportation effects will hose your INS until you can recalibrate it from a known location.
Anaraxes is offline   Reply With Quote
Old 07-27-2019, 06:16 AM   #5
Celjabba
 
Join Date: Sep 2006
Location: Luxembourg
Default Re: Inertial Guidance, What Is It? (In GURPS Terms)

Inertial compass defined as

Absolute Direction (does not include magnetic Compass, does not include the retracing path ability, does not include the body sense bonus, require Absolute timing, require regular calibration or became more and more innacurate, require calibration after teleport or other)

is imho easier to stat as just a perk granting a bonus to navigation.

If you add a compass, a memory unit, drop the absolute timing requirement, you now have Absolute direction (limitation:require calibration)

An integrated map display is separate and either an accessory perk or a modular ability granting a huge bonus to navigatiion.

Last edited by Celjabba; 07-27-2019 at 08:05 AM.
Celjabba is offline   Reply With Quote
Old 07-27-2019, 07:59 AM   #6
RyanW
 
RyanW's Avatar
 
Join Date: Sep 2004
Location: Southeast NC
Default Re: Inertial Guidance, What Is It? (In GURPS Terms)

I'd just call it Absolute Direction with no modifier. The fluff is different, but the effects are the same.
__________________
RyanW
- Actually one normal sized guy in three tiny trenchcoats.
RyanW is offline   Reply With Quote
Old 07-27-2019, 08:55 AM   #7
Humabout
 
Humabout's Avatar
 
Join Date: Aug 2008
Default Re: Inertial Guidance, What Is It? (In GURPS Terms)

It's just 3D Spatial Sense. You get all 3 dimentions with the same equipment you need for a 2D version, and the filter used to combine your sensor data and reduce error doesn't run significantly slower for handling the extra dimension at TL 8.

Note that it doesn't natively maintain a history of where you've been - just where you are and which way you're pointed in 3D space relative to some predefined coordinate system. It wouldn't be hard to add a log of past states, though.

It's also worth noting that, as described, you still need GPS, radar, or some other outside reading for position and velocity to do positional estimation. Attitude estimation can be done with accelerometers, gyroscopes, and magnetometers within a fixed magnetic field. This is because Euler integration of acceperation also adds in the error present in sensor readings, causing drift in readings that ultimately leads to inaccurate results. This takes as little as about 15 minutes with off-the-shelf IMUs available online.
__________________
Buy My Stuff!

Free Stuff:
Dungeon Action!
Totem Spirits

My Blog: Above the Flatline.

Last edited by Humabout; 07-27-2019 at 09:02 AM.
Humabout is offline   Reply With Quote
Old 07-27-2019, 07:40 PM   #8
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: Inertial Guidance, What Is It? (In GURPS Terms)

Quote:
Originally Posted by scc View Post
I want to know what this ability would be in terms of Advantages. At first I thought it simply be Absolute Direction with a limitation, but as I've realized recently that having it allows you to build a map of where you've been in some unknown place, that can't be right, so anyone got any ideas or have I stumbled upon something we somehow don't have yet?
Absolute direction/3d spatial sense plus a point in cartography? It's hard to account for 'always retrace a path you have followed in the past month' without something strongly resembling a mental map, and then add cartography so you can also make a map other people can use.
__________________
My GURPS site and Blog.
Anthony is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 06:31 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.