Submitted by brad on Thu, 2004-10-28 13:23.
Soon as it was out, I bought the EOS D20. I sold my D60, which I had replaced my D30 with, so I am obviously generally pleased with Canon's line. The new camera has a lot over the D60 -- 2 more megapixels (or 3500 high for panoramas), much better low-light shooting ability with low-noise high-ISO, and fast shooting (5 frames/second for 25 frames.) It also has better focus, better controls, and an orientation sensor, something I've been wanting for a long time.
The orientation sensor is botched though. The menu offers the ability to rotate pictures in the display based on the orientation. Not what I want, so I turned it off. Sadly, this ended up turning off even the recording of the orientation sensor, which is stupid. You want this screen rotate off because it makes the picture half the size to do it, and it's wrong if the camera is being held in portrait mode, as it may be on a tripod. The right thing to do would be to rotate based on the camera's orientation -- if I shot in portrait and I show in portrait it should fill the screen. However, generally I don't want the display rotate on the small screen, I can just turn the camera in my hands.
Turning off the sensor recording without this mode is incredibly stupid, I hope they fix that in future firmware. Frankly, I would have them rotate the actual picture as they store it with a lossless rotate. It's a pain to have to run special software (theirs sucks) to convert all the pictures after you shoot them. Part of why I wanted the software was to get away from this annoying task.
For a decade or more, video cameras have come with a small pinhole next to the screw tripod mount. Mounting plates have a pin that goes in there to mount the camera securely. Why do still cameras never come with this hole? It would make the mounting much more secure.
The camera has a full zoom in, something the Canon DSLRs were very slow to adopt. But nobody yet has a "smart" zoom-in, which zooms directly to a 1:1 view of the highest contrast element in the scene, or alternately to one of the focus points that it did the autofocus on (though that can move.) This would let me quickly see if shots were blurry or not. If the highest contrast portion of the scene is not in focus, the whole thing is blurry. If it's in focus but was not at the distance of my subject, I know I shot the wrong thing, and can correct it now. You don't see that on the small screen.
Can't say I'm thrilled with combining the on/off for the back-wheel with the on-off for the camera. I always want that wheel on.
And yes, it's time for DSLRs to get live preview. They can do it, they already split the beam a couple of ways -- most of the light to the eyepiece, but part of it to the autofocus/light meter instruments. Low-res sensors are now cheap enough that you could put one in to perform all those roles and also allow live preview. Live preview isn't just for cheap point and shoot cameras. Yes, through-the-lens is better for composing most shots, but I love how on my G5 I can shoot in places I can't get my eye to the viewfinder, like when the camera is held above my head, at my waist, on the ground, on my knee for stability etc.
And nobody has yet imported features like Nikon's Best-Shot-Selector, a bracketing mode which picks the least blurry of a series of shots in low light. Of course you can do this by just keeping all the shots.
But as I said, I am generally satisfied, but it doesn't mean they can't keep improving.
Submitted by brad on Mon, 2004-10-25 17:08.
Many people like the idea of soda fountains, but the official fountains that mix soda and pre-mix concentrate are quite expensive and work to maintain.
To gain some of the convenience and efficiency, how about a quasi-real fountain using existing 2-liter pop bottles? Such a fountain would be designed to look like a regular one. Inside, ordinary 2-liter bottles would be attached. In a "party" model, they would just be in an icebox, in a full-time model it would have refrigeration.
To attach the bottles, their caps would be removed and a special cap screwed on that would have two hoses -- one for pop to come out, and the other for gas (CO2 or air) to come in to push out the drink. A CO2 cylinder could power this, or an air pump if you want battery power. Gravity might be able to do it but pressure certainly could.
The special caps would have another quick connect interface that lets them be turned upside down and snapped into place. Alternately, the bottles could be in another orientation as long as the feed tube can reach their bottom.
You might want to be able to have two bottles of the same drink feed the same fountain to give more capacity and the ability to drain one and then the other so that they can be "hot swapped" (really cold but you know what I mean.) Or people might prefer to be able to offer lots of different drinks, but just 2L of each.
The goal of this design is to be very cheap. The one based on ice and CO2 cartridges would be very cheap and need no power -- more of a party amusement, but also an efficient way to give people only what they need.
Of course you could just empty the bottles into reservoirs, but then you need a way to clean them. Cleaning the tubes could be done with an attachment for a garden hose to flush them, and the caps could go in a dishwasher.
This is my lowest tech idea yet...
Submitted by brad on Sat, 2004-10-16 13:36.
I've written about a few plans to get rid of the headache (and travel killer) that airport security has become. One of the great curses is that because you can't predict how long security might take, most people end up arriving way, way ahead of their flight in case the line is long, but often they clear it in just a few minutes. (Ditto the immigration/customs line at Canadian airports going to the USA.)
So here's another idea -- appointments for going through airport security. When you use web check-in (which many airlines now support) or even at the gate, you would be allocated an appointment in the latest available slot some period (say 20 minutes) before boarding ends for your flight. Appointments would be spaced at slightly more than the average time to clear a passenger through security.
This would work because there would be two lines at the security gate. One for people with appointments, one for those without (or who missed their appointment.) You could only enter the appointment waiting zone in the 10 minutes prior to your appointment, and presuming 30 seconds per party, that would mean it would hold about 20 people. An agent would check your bar-coded appointment slot in letting you in.
When your time comes (or at any free time) you would be taken through at the head of the security line. If somebody needs extra security (random search, suspect item) that of course delays the station they are going through, but the other stations are free to take the person with the next appointment. Only if all stations got bogged down with problem cases would people in the appointment line not go through at close to their exact appointment time. read more »
Submitted by brad on Wed, 2004-10-13 06:04.
I have often heard it said that being a Senator is a good stepping stone to President of the USA. Research shows this to be really false, and that's bad news for Kerry. Oh, many sitting senators run for President, but for over 120 years, they have rarely and barely won.
The one exception that proves the rule is John F. Kennedy, the only sitting senator of the modern political era to be elected President. And barely so -- there are many who still say JFK stole the election, and in any event it was one of the closest in history before Bush/Gore. JFK was also a congressman, and he sat out a few years of his Senate career due to back problems.
Before Kennedy we have to go back 84 years, and out of the modern era, to Warren Harding, who won handily from the Senatem then died in office. And before that you go to Benjamin Harrison, who lost the popular vote but won the electoral vote.
The first century of U.S. history has many Senator->President transitions, which may have created this myth.
Some suggest that the reason is that a Senator has a long voting record which can be used against him or her, and that does appear to be the case. But the suggestion it's a good stepping stone is false.
(Also worth noting that Kennedy, Harding and Harrison did not defeat sitting Presidents. Defeating sitting Presidents is of course hard to do, but Carter and Clinton, who did it, were both Governors.) I didn't research enough to find out how far back you have to go to find a Senator unseating the President. read more »
Submitted by brad on Mon, 2004-10-11 12:10.
Well, a couple of weeks ago when I announced the phone project at Burning Man, I implicitly was linking to my new galleries for Burning Man 2004. However, let me officially announce those galleries now, plus the addition of a new gallery today.
Submitted by brad on Thu, 2004-10-07 05:58.
An out of left-field idea. It doesn't happen a lot, but one of the things people fear deeply is being bitten by a shark. Sharks sometimes bite surfers, because, it is suspected that 4 paddling arms lying on a surfboard triggers the "tasty seal" match in the shark's brain.
(Reportedly sharks don't actually like how we taste that much, and have spit out human limbs they bit off. I dunno, but somehow that's adding insult to major injury.)
Anyway, to stop this there are some products on the market. One is a set of decals in the black and white stripe patterns of poisonous fish sharks don't like to eat. Another is a set of electrodes that send out a strong electric field which sharks hate (they have electric sensing organs that most fish don't.)
Here's another idea, for all the surfboard shark repellant readers of my blog out there. Since the shark looks up at the board against the glittering surface, patterns on the bottom may not be enough. But what about new bright but low power LEDs? Possibly an animated pattern moving over the LEDs to say "not food" to the shark. First of all such light is highly non-natural (at least not from prey) and can be made to move in very artificial ways, or natural ways that signal non-prey. And today, the power for it is not very much. Here's where we need the advice of all the trained icthyologists reading the blog.
Submitted by brad on Tue, 2004-10-05 08:52.
Ok, it's not like we're crying for a new word, since we already have so many: Generation Y, Generation Next, Boomlets, Echo-boomers, Millenials etc. But still, I like to throw out new words so mine is "Boomerangs" which nicely captures the concept of the rebound of the Baby Boom, and a few other concepts as well.
Submitted by brad on Mon, 2004-10-04 07:11.
I'll be speaking at three conferences in the near future, and can offer discounts to blog readers for two of them.
Coming up October 19, I will be speaking on the future of SIP, and whether IAX2 or Skype might kill it, at the Pulver Voice on the Net conference in Boston.
Nanotech and Privacy
Later that week, I will chair day 2 (Sat, Oct 23) of the Foresight Conference on Advanced Molecular Technology in Washington, DC. Friday is about technology, Saturday is about Applications, Sunday is Policy. On Saturday I will deliver a talk on the merits of privacy which will lead into a debate about privacy and surveillance in the nanotech world.
Blog readers who wish to attend this conference can get a 30% discount by using registration code BRAD30-CP.
Debating David Brin on Privacy
Then, on November 6, I will do a similar debate at Accelerating Change 2004, this time with noted Science Fiction author David Brin (who also wrote "The Transparent Society.) Blog readers can get a $50 discount before Oct 20 by using the code AC2004-BRAD.
After that it's off to the Vintage Computer Festival, and Hackers.
Burning Man Decompression
Plus, before all that, this Sunday I will be at the Burning Man Decompression party, a small taste of Burning Man on the city streets. I will display my latest giant photographs, plus my Star Map and with luck we will have the phone booth in operation, though it won't be as out of place on a city street.
EFF Salon on E-Voting
And finally, though I won't be speaking at it, the EFF has restarted our BayFF series of talks and salons on major issues. The next is Tuesday, October 12, 7pm at the 111 Minna Gallery in San Francisco on the subject of e-voting and the upcoming election. Free, but how much would it hurt you to donate?
Submitted by brad on Sun, 2004-10-03 11:49.
Tested my UPS systems and found them wanting in Friday's 10 hour Cupertino blackout. Last week I wrote about my longtime desire for a PC power supply that let you plug in an external battery for a cheap, long lasting UPS. But here are some other ideas.
Generally you don't want to plug your monitor into your UPS, because it will drain it faster, which is pointless if you are not there. Better energy-conserving monitors with screen-blanking screen savers can do something about this, but why waste any power on a monitor you're not looking at. I've taken to leaving the monitor off of the UPS power, and then when I come to the computer to do something, plugged the monitor into the UPS. Of course that can require a flashlight and wastes precious time.
So let's have a plug on the UPS that is switched. By default it only takes mains power, even during a failure. But during a failure you can push a button and it switches to the backup power. Perhaps have more than one of these, and plug all your optional devices into them. (For workstations, for example, you may want to only power network hubs or DSL modems when you are there, though I usually go the reverse path.)
Of course, since often the computer has a data link to the UPS, you could even have the computer tell the UPS to power on the optional plugs if the person is at the keyboard.
One could also build a fancy switched plug to do this though I don't know if anybody makes such off the shelf. That might be a simpler product. read more »
Submitted by brad on Thu, 2004-09-30 05:36.
We've gotten used to a painful, privacy invading security process when we fly. But why should we do this for shot-hop, small aircraft. Those ones on the 20 seat Canadair Business Jets and similar. Secure the cockpit with a sealed door and arm the pilot so that terrorists can't take control of the plane. Put in sealed transponders so ATC knows if the plane goes astray. Give the pilot a "disable" button that limits what can be done with the plane in the event of attempted hijack.
Other than that, give it no more security than a bus or train. Just show your ticket, or pay cash, and walk on, possibly going through no more than the metal detectors used at things like baseball games and museums. Possibly not even that.
Yes, evil people could smuggle a gun, and suicide terrorists could put a bomb in their luggage. And kill 15 people. Which would be horrible, but frankly there are a lot more dangerous targets out there for the terrorist willing to kill himself, where a lot more damage can be done, and a lot more people killed. Hell, there are more tempting targets where you don't have to kill yourself. It makes little sense to waste resources blowing up tiny planes.
Which means we should not go nuts securing them. This already takes place at small airports and on general aviation. I've seen post-911 stories of people just walking onto small corporate jets with no ID or search, as well as other private planes and charters. Combine that with other ideas on efficient plane operation and you might just have a very popular airline for flights under 500 miles.
Submitted by brad on Mon, 2004-09-27 13:07.
I like fine camera lenses, but the best quality are very expensive. There are many things that are hard to do in a good lens -- you want a sharp image, of course, over the full flat plane. Over the whole image plane you want low flare, high contrast and low chromatic abberation (ie. red and blue focus in the same spot.) And you want low distortions.
Most camera lenses try to be "rectilinear." That means they try to make a straight line straight in the image. This isn't actually natural, due to perspective straight lines are not straight.
So I wonder if we might soon see a new lens where no effort is made to fix distortions or make the image rectilinear, and all effort goes into the other factors. You are thus expected, with every image, to do digital post-processing to get a non-distorted rectilinear image. That will mean some small loss of image quality at the edges of the image, but probably a less distorted image than ordinary lens physics can deliver -- and a lot less cost -- in exchange.
Of course, this would primarily be for digital cameras, but a film user could also use the lens if they planned to scan their film for digital processing, as most do these days.
Down the road, each lens might contain within it the specifics of its own particular distortions, and the camera might be able to fetch this and either process directly or store it with the image for post-processing. Indeed, the lens might be a cheaply made lens with distortions due to the poor quality elements, or it might be a fine lens with deliberate distortions. (I have wondered if some P&S digicams might be doing this already.) read more »
Submitted by brad on Sun, 2004-09-26 15:28.
A lot of our democratic process involves our elected officials voting and presiding over things that voters are not going to change their vote over. Oh, they are important things, and the voters actually do care about them, but they are not going to change many votes.
That's especially true now. In deciding whether to re-elect your congresscritter, is how they voted on say FCC spectrum policy going to make a difference to you, compared to their stance on bigger issues like the war and the economy? Even when spectrum policy matters a lot to you?
The result of this is that there is no accountability on these committees, and little downside to selling your vote to somebody who does matter -- a big contributor who can give you the money you think you need to win votes. read more »
Submitted by brad on Thu, 2004-09-23 13:03.
(Baby I tried to fly again but I was…)
First Class then Deported
Oh baby it’s a wide world
(And it’s hard to get by Bangor, if you have to fly, Girl)
I’m being followed by an F-16 Shadow
(And if I ever lose my rights…)
(Everyone jump off the ) Siezed Plane
(Suspected Terrorist) Warning has Broken
Oh Very Muslim, will you please leave us this time?
Submitted by brad on Wed, 2004-09-22 07:21.
Generally, getting a case to use a camera underwater is expensive. The case has to be custom made for the particular camera, and it has to be full of waterproof push-through button-pushers for all the major controls. Digital cameras have helped a lot, since they can shoot far longer on a "roll" and things like zoom are electronic. They also sell in enough volume that some cases have gotten down to reasonable prices.
But more is possible because most modern digital cameras feature complete electronic control, either by USB or via infrared. This should make it possible to build a generic underwater camera case for whole classes of digital cameras of a certain size. The case itself can be very simple, with no holes or button gaskets. For cameras without infrared remote (or where the IR remote does nothing but a couple of buttons), a small USB to IR converter would allow complete control.
The box is simple, the real brains would be in an underwater-capable IR remote control carried or mounted on the outside of the case. It would need personality modules for new models of cameras but otherwise could be pretty much the same as well.
So you get a much simpler box and you get mass production because you can sell it for any camera. And you can keep it for your next camera. It's a bit bulkier, but that's about it. And it can offer more controls, even some controls that aren't even on the camera in some cases.
Zoom can be a bit tricky. You want to avoid glare off the plexi at the front when the lens isn't up against it. It's possible that might be designed to telescope when you change zoom settings, or the camera itself might gently move in an inner frame. Or it might just have a black bellows "hood" in the space between the lens and the view panel. This problem also exists in custom cases of course.
The same idea could also be applied to above-ground protection in harsh environments (snow, rain, dust etc.) for expensive cameras. There you don't need a pressure seal, just a thick bag with the same remote ability. Shoot happily in the rain.
Submitted by brad on Tue, 2004-09-21 09:30.
RVs come in all sizes, from 40’ bus to towable pop-up. But what about inflatable in a trunk in the back of a minivan?
Setting up and tearing down tented campsites is a pain, and there are instant-setup tents and even some inflatable tents. But what about a super-duper inflatable tent, designed for car-camping.
In the cabin-tent structure with high-pressure frame would also be (at lower pressure) one or more built in airbeds (that you leave the bedding on), an inflatable couch or chairs, wiring for LED or fluorescent lights in the roof with switches, 12v power jacks etc. On the outside might be an inflatable sink with 12v pump and drain hose and outside inflatable chairs. There would be an “air pressure bus” with quick-connects and turnable valves for each component. Inflation would be pushbutton, deflation might require turning values as you deflate components but still simple. Once deflated, the whole thing — components, bedding and all — would roll up and fit into a trunk or large suitcase that would fit in the back of a minivan or SUV. It would not be designed to be small or light like most tents.
It could also be designed to sit in a hitch holder, along with a bike rack. Add a portable toilet, camp stove, ice chest and folding tables (inflatables are not solid enough.) Ideally wire a special jack into the van battery, and replace the van battery with a marine battery (deep cycle and starting).
The goal: open the crate, open the valves and start the compressor. In a few minutes, a living space is erect. If needed, put in weights or stake it down. In the morning, start the vacuum on the internal components, then turn the valves to drain the support members, roll it up, bedding and all, and go.
I believe this could easily sell for $1,000 or more. It would be almost as easy as a pop-up camper, but best of all you would not be towing something. It would pay for itself for families on a cross country road trip pretty quickly. The key is to not think of it as a tent but as an RV.
Submitted by brad on Mon, 2004-09-20 09:23.
Vernor Vinge (Vin-GEE)(whose 1993 novel "A Fire Upon the Deep" I published in hypertext form) coined the term "singularity" to refer to a future social and technological shift so profound and vast that those who come before it are actually incapable of understanding it.
This is an important concept, one that plays out in his novels and the writings of many others, and it needs a term. But this term has ended up not being ideal.
Scientists already have a meaning for the word of course, but it is more specific. It refers to a point where a function is undefined. For example, dividing 1/x has a singularity at 0, since 1/0 is undefined. More to the point, 1/x also increases exponentially towards infinity as you approach 0. These concepts of rapid acceleration, and the inability to extrapolate past a singularity inspired the metaphor Vinge was trying to convey.
Other forms of singularity can include any sharp corner in a function (where the derivative is undefined) and in areas within a black hole (where are normal equations of physics are undefined.) However, the non-scientific public does not understand these mathematical meanings, and thus don't quickly grasp even the metaphor.
An example of such a metaphorical singularity would be the creation of language. Pre-verbal proto-humans simply can't understand the beauty of poetry at all, no matter how much time you would have to explain it.
The "Vinge" singularity deoes not involve a discontinuity or undefined point in history. Instead, the path is continuous. You can't easily point to a specific second and say "There is the singularity where language capable of Shakespeare arose."
So the term is wrong for those who understand the mathematical meaning and meaningless to those who don't. We should seek a better term.
I welcome suggestions from readers. I think the important thing to convey is perhaps the metaphor of the "blind corner" -- a sharp, but not impossibly sharp turn which you can't see around until you get there. The ideal metaphor should also convey the acceleration of change which causes the phenomenon, and this does not. That is more akin to flying off a cliff, or the planes that turn to submarines in the new "Sky Captain" movie.
Submitted by brad on Thu, 2004-09-16 08:56.
One core reason I haven't blogged much in the last while is the flurry of activity regarding my annual trip to Burning Man. I've prepared a page about one of my too-many projects this year, which was to build an incongruous phone kiosk in the middle of the desert which worked and let you call anybody in the world for free. It was battery powered, and used 802.11 and Voice over IP combined with a satellite internet connection.
The reaction was remarkable and I have made a set of pages about phone booth and reaction to it. including pages on the building of it, galleries of photos of people using it (including, of course, naked people) and maps of all the places people called.
(I will probably submit this to slashdot next week to test my server!)
Now my goal was to take some highly familiar technology and put it in a place where it seemed impossible. And indeed, most people refused to believe it was "real" since there are other joke phone booths at Burning Man. Their disbelief and shock were what made it fun, as well as the emotional experiences and gratitude that came when people heard distant voices. It was a taste, in a small way, of what the phone meant when it was new.
I have much more stuff about Burning Man to blog in the days to come.
Submitted by brad on Tue, 2004-09-14 09:25.
I finally watched the closing ceremonies yesterday (did not see them while at Burning Man, obviously.) I liked the blinky balls that the children and audience members had, and the sense that the flame lit the LED ball. But it was just manual, people pushed buttons.
It occured to me it would not be too expensive to make an LED blinky that worked a bit like flame. While it was on, it would transmit a particular signature code in its blinking. If another blinky got close enough to see this brightly enough, it would detect it and turn itself on for some period of time. You could tune the range, it's just a photoresistor.
That way they could "light" their neighbours the way a flame does, and the flame would pass along. With the range tuned to a few feet, the lighting would have propagated through the audience at some speed (you could define what the speed would be.)
This would also be a fun rave/party favour. You might be able to light your own or you could light from somebody else. Perhaps after too long alone the blinky would go out and need to be lighted from somebody else's, encouraging socialization.
Submitted by brad on Mon, 2004-09-13 11:53.
We all would love solar power to work better, but it's hard to have it make economic sense yet, at least if you're near the grid. A solar panel takes 4 years just to give back the energy it took to build it, and it never pays back the money put in if you compare it to putting the money into the stock market. And that's with full utilization. If you use panels and batteries, any time your batteries are near full the power is being discarded, and you also have to replace your batteries every so often and dispose of the old lead-filled ones. Yuk. A grid-tie can use all the power of a panel but that's an expensive, whole-house thing.
But here's a start -- a solar-using PC power supply. My PCs, like many folks', are on all day, including the peak-demand heat of the day. Desktops draw anywhere from 50 to 200 watts even when idling.
So make a PC power supply that has 3 external connections. One for the wall plug. And two optional ones, one for a 12v solar panel and one for a battery. Then sell it with a 50w or 100w solar panel -- most importantly, the panel should not ever generate more power than the PC uses.
Because of that, during the bright part of the day, the panel will be providing most, or just barely all, of the power for the PC. The wall plug will provide the rest. At night, the wall plug would provide all the power. It's a grid-tie but it doesn't feed power back to the grid, it just reduces demand on it. The 100w panel takes 100w off the grid load during the peak demand times. And we use every watt the panel generates, we never throw any away. read more »
Submitted by brad on Thu, 2004-09-09 13:49.
First entry in a while due to trip to Burning Man ... more on that later. This time I returned to RV rental, after 2 years in a tent, so I thought I would make some notes on that.
It amazes me how little attention mainstream RVs pay to what is called "dry camping" -- away from electrical and water connections. Yes, they have batteries, tanks and generators, but it's very rare to see an RV use fluorescent lights, for example, even though they are available in 12v form and take 15% or less of the power of the incandescent lights they currently use. If running off batteries this is a no-brainer.
Inverters are also cheap these days, and more efficient. Some draw almost nothing now when not loaded, so a built in inverter to run 110v gear efficiently off the batteries also makes sense. As noted, a 1kw inverter is today quite cheap, and could even run the microwave, though you would not want to do that much. An automatic system to run mostly from battery but start the generator on-demand during daytime hours if it gets low could make sense.
Solar kits are sold for RVs but are rare and rarely standard. It also amazes me that they don't come standard with built in liquid soap dispensers, paper towel racks and other things to keep the commonly used stuff secure.
We have found it handy to use the rubbermaid (or similar) plastic storage boxes to put multiple boxes in the overhead storage. Pull out drawers would also make sense here. Each time you move you have to "rig for silent running" and some RVs we have rented come with metal blinds that will clank and clank unless you stuff towels into them.
The latest RVs only fill their water tank from a standard pressurized hose. Turns out that's a curse at burning man because the water truck is not allowed to have such a fixture due to the risk of backflow from an unknown tank. Doubt we will see a fix for that as it is an unusual problem.
RVs come with very low precision monitor guages, from before the digital age. They show you that your tanks are at 0, 1/3, 2/3 and full, for example, and likewise for your battery. On the fresh water tank they could measure flow through the water pump to get a much more accurate figure, and if they detected if the toilet was the use, they could also know how much was likely in the gray tanks. The black tank (sewage) sensors have been broken on every RV I have ever encountered, they gum up with toilet paper. You would think after decades of having unusable sensors they would devise some other method, such as a pressure sensor under a heavy membrane, or bouncing sound waves or light off the top of the sewage. You can of course shine a flashlight down the toilet, but that's harder to judge than you might think and of course not very pleasant.
Measuring the battery accurately is of course a much easier task, and I use my voltmeter to do it. You could also do a full coulomb counter like laptops do to really accurately measure charge level and the condition of the battery to find out when it's time to replace. None of this stuff is expensive in the modern digital world, but RV designers still think in 80s technology, I surmise.
It's also common to find just one 12v jack in an RV and at most 2, usually where TVs will go. They assume RV owners will not be using much 12v equipment even though it's quite common nowadays.
In order to protect the batteries when camping off-grid, there should be timers or automatic shut-offs of lights if voltage goes below certain limits. Many an RV camper has left a light on and found their battery drained. If they are there and the timer trips, they can just manually turn it on again.