I'm interested in building a 3D model of our solar system for web use (probably with AS3 and papervision) and have been looking into how I would go about encoding the planetary positions. My idea was to download the already calculated positions from NASA as calculating the positions myself seems a but overcomplicated. I'm not sure though whether I should use a helio centric or an earth centric encoding.
I wanted to know if there are any one with any experience in this. Which approach would be better? The NASA JPL website seems to have the positions of all the major bodies in our solar system as earth centric. I can see this becoming a problem later on though when adding Voyager and Mars Lander missions to the model?
Any feedback, comments and links are very welcome.
EDIT: I have a rough model running that uses heliocentric coordinates, but I haven't been able to find the coordinates for all planets in this format.
UPDATE:
I don't have a lot of detail to provide for know because I really don't know what I'm doing (from the space point of view). I wanted to get a handle on 3D programming, and am interested in space. The idea was that I would make a rough solar system simulator with at first all the planets and their orbiters (maybe excluding satellites at first). Perhaps include a news aggregator and some links to news/resources and so on. The general idea would be to allow people to click around and get super excited about going to the moon and Mars (for a starter).
In the long run I hopefully would be able to add in satellites and the moon missions (scroll back in time to the 70's and see the moon missions).
So to answer Arrieta's question the idea was not to calculate eclipses but to build an easy to approach, interactive space exploratorium, and learn some 3D and space related stuff on the way.
Glad you want to build your own simulator, but depending on what you want to do it may be far from an easy task. The simplest approach is as follows:
Download the JPL-DE405 ephemerides and the subroutines for retrieving the planetary positions (wrt Solar System Barycenter).
Request for timespan, compute the positions, and display them to the screen in a visually appealing manner
Done
Now, why would you want to do this? If you want to view the planet's orbits, that's it. You are done. If you want to compute geometric events (like eclipses, or line-of-sight, or ilumination) then you are in a whole different ball game. That's astronautics, and it is not simple.
Please be more specific. The distinction you make of "geocentric" or "heliocentric" coordinates really has no major difficulty involved. If you have all the states in heliocentric frame, you can compute the geocentric frame by simple vector subtraction. That's not the problem! The problems are a thousand more, but you need to be specific so we can provide more guidance.
JPL has provided high quality ephemerides for decades now, and we have a full team of brilliant people working on it. It is one of the most difficult things to get right!
Again, provide more details or check out other sources of information.
Please google "Solar System Simulator" (done here, at JPL) and see if it fulfills your needs.
Cheers.
It may be worth you checking out the ASCOM Platform (we also have a stack exchange site called ASCOM Answers).
The ASCOM Platform has several useful libraries for doing this sort of thing.
USNO NOVAS (Naval Observatory Vector Astrometry)
Kepler orbit engine
The USNO/NOVAS stuff was originally written in C and we've wrapped it up in .NET for ease of use from C# and VB.
As an added bonus (actually it's the raison d’être for ASCOM), the Platform makes it easy for you to control things like telescopes, it's used by Microsoft's World Wide Telescope for exactly that purpose. I tmight be a fun extension to your model to be able to point a telescope at things.
I'd probably start (well, I did a while back) with heliocentric coordinates and get a few of the planets up and running. But sooner or later you'll want to write a heliocentric-to-geocentric coordinate conversion routine, and its inverse. For some bodies, such as artificial satellites the geocentric coordinates will be easier to deal with.
You can use the astro-phys api to get a JSON formatted state vector for all the planets. It calculates them using JPL's de406 so it's pretty accurate and uses the solar system barycenter.
Although, if you know where the sun is relative to the earth and you're in a geocentric model, you can subtract the position of the sun from all of the bodies (including earth) to be heliocentric.
Related
I'm using joint positions from a Kinect camera as my state space but I think it's going to be too large (25 joints x 30 per second) to just feed into SARSA or Qlearning.
Right now I'm using the Kinect Gesture Builder program which uses Supervised Learning to associate user movement to specific gestures. But that requires supervised training which I'd like to move away from. I figure the algorithm might pick up certain associations between joints that I would when I classify the data myself (hands up, step left, step right, for example).
I think feeding that data into a deep neural network and then pass that into a reinforcement learning algorithm might give me a better result.
There was a paper on this recently. https://www.cs.toronto.edu/~vmnih/docs/dqn.pdf
I know Accord.net has both deep neural networks and RL but has anyone combined them together? Any insights?
If I understand correctly from your question + comment, what you want is to have an agent that performs discrete actions using a visual input (raw pixels from a camera). This looks exactly like what DeepMind guys recently did, extending the paper you mentioned. Have a look at this. It is the newer (and better) version of playing Atari games. They also provide an official implementation, which you can download here.
There is even an implementation in Neon which works pretty well.
Finally, if you want to use continuous actions, you might be interested in this very recent paper.
To recap: yes, somebody combined DNN + RL, it works and if you want to use raw camera data to train an agent with RL, this is definitely one way to go :)
I am not sure this kind of question has been asked before, and been answered, by as far as my search is concerned, I haven't got any answer yet.
First let me tell you my scenario.
I want to develop a chess game in Flash AS3. I have developed the interface. I have coded the movement of the pieces and movement rules of the pieces. (Please note: Only movement rules yet, not capture rules.)
Now the problem is, I need to implement the AI in chess for one player game. I am feeling helpless, because though I know each and every rules of the chess, but applying AI is not simple at all.
And my biggest confusion is: I have been searching, and all of my searches tell me about the chess engines. But I always got confused in two types of engines. One is for front end, and second is real engines. But none specifies (or I might not get it) which one is for which.
I need a API type of some thing, where when I can get searching of right pieces, and move according to the difficulty. Is there anything like that?
Please note: I want an open source and something to be used in Flash.
Thanks.
First of all http://nanochess.110mb.com/archive/toledo_javascript_chess_3.html here is the original project which implements a relatively simple AI (I think it's only 2 steps deep) in JavaScript. Since that was a contest project for minimal code, it is "obfuscated" somewhat by hand-made reduction of the source code. Here's someone was trying to restore the same code to a more or less readable source: https://github.com/bormand/nanochess .
I think that it might be a little bit too difficult to write it, given you have no background in AI... I mean, a good engine needs to calculate more then two steps ahead, but just to give you some numbers: the number of possible moves per step, given all pieces are on the board would be approximately 140 at max, the second step thus would be all the combination of these moves with all possible moves of the opponent and again this much combinations i.e. 140 * 140 * 140. Which means you would need a very good technique to discriminate the bad moves and only try to predict good moves.
As of today, there isn't a deterministic winning strategy for chess (in other words, it wasn't solved by computers, like some other table games), which means, it is a fairly complex game, but an AI which could play at a hobbyist level isn't all that difficult to come up with.
A recommended further reading: http://aima.cs.berkeley.edu/
A Chess Program these days comes in two parts:
The User Interface, which provides the chess board, moves view, clocks, etc.
The Chess Engine, which provides the ability to play the game of chess.
These two programs use a simple text protocol (UCI or XBoard) to communicate with the UI program running the chess engine as a child process and communicating over pipes.
This has several significant advantages:
You only need one UI program which can use any compliant chess engine.
Time to develop the chess engine is reduced as only a simple interface need be provided.
It also means that the developers get to do the stuff they are good at and don't necessarily have to be part of a team in order to get the other bit finished. Note that there are many more chess engines than chess UI's available today.
You are coming to the problem with several disadvantages:
As you are using Flash, you cannot use this two program approach (AFAIK Flash cannot use fork(). exec(), posix_spawn()). You will therefore need to provide all of the solution which you should at least attempt to make multi-threaded so the engine can work while the user is interacting with the UI.
You are using a language which is very slow compared to C++, which is what engines are generally developed in.
You have access to limited system resources, especially memory. You might be able to override this with some setting of the Flash runtime.
If you want your program to actually play chess then you need to solve the following problems:
Move Generator: Generates all legal moves in a position. Some engine implementations don't worry about the "legal" part and prune illegal moves some time later. However you still need to detect check, mate, stalemate conditions at some point.
Position Evaluation: Provide a score for a given position. If you cannot determine if one position is better for one side than another then you have no way of finding winning moves.
Move Tree and pruning: You need to store the move sequences you are evaluating and a way to prune (ignore) branches that don't interest you (normally because you have determined that they are weak). A chess move tree is vast given every possible reply to every possible move and pruning the tree is the way to manage this.
Transpotion table: There are many transpositions in chess (a position reached by moving the pieces in a different order). One method of avoiding the re-evaluation of the position you have already evaluated is to store the position score in a transposition table. In order to do that you need to come up with a hash key for the position, which is normally implemented using Zobrist hash.
The best sites to get more detailed information (I am not a chess engine author) would be:
TalkChess Forum
Chess Programming Wiki
Good luck and please keep us posted of your progress!
I am going to be working on self-chosen project for my college networking class and I just had a couple questions to help get me started in the right direction.
My project will involve creating a new "physical" link over which data, in the form of text, will be transmitted from one computer to another. This link will involve one computer with a webcam that reads a series of flashing colors (black/white) as binary and converts it to text. Each series of flashes will simulate a packet of data. I will be using OSX an the integrated webcam in a Macbook, the flashing computer will either be windows or osx.
So my questions are: which programming languages or API's would be best for reading live webcam data and analyzing the color of a certain area as well as programming and timing the flashes? Also, would I need to worry about matching the flash rate of the "writing" computer and the frame capture rate of the "reading" computer?
Thank you for any help you might be able to provide.
Regarding the frame capture rate, Shannon sampling theorem says that "perfect reconstruction of a signal is possible when the sampling frequency is greater than twice the maximum frequency of the signal being sampled". In other words if your flashing light switches 10 times per second, you need a camera of more than 20fps to properly capture that. So basically check your camera specs, divide by 2, lower the resulting a little and you have your maximum flashing rate.
Whatever can get the frames will work. If the light conditions in which the camera works are gonna be stable, and the position of the light on images is gonna be static then it is gonna be very very easy with checking the average pixel values of a certain area.
If you need additional image processing you should probably also find out about OpenCV (it has bindings to every programming language).
To answer your question about language choice, I would recommend java. The Java Media Framework is great and easy to use. I have used it for capturing video from webcams in the past. Be warned, however, that everyone you ask will recommend a different language - everyone has their preferences!
What are you using as the flashing device? What kind of distance are you trying to achieve? Something worth thinking about is how are you going to get the receiver to recognise where within the captured image to look for the flashes. Some kind of fiducial marker might be necessary. Longer ranges will make this problem harder to resolve.
If you're thinking about shorter ranges, have you considered using a two-dimensional transmitter? (given that you're using a two-dimensional receiver, it makes sense) and maybe have a transmitter that shows a sequence of QR codes (or similar encodings) on a monitor?
You will have to consider some kind of error-correction encoding, such as a hamming code. While encoding would increase the data footprint, it might give you overall better bandwidth given that you can crank up the speed much higher without having to worry about the odd corrupt bit.
Some 'evaluation' type material might include you discussing the obvious security risks in using such a channel - anyone with line of sight to the transmitter can eavesdrop! You could suggest in your writeup using some kind of encryption, a block cipher in CBC would do, but would require a key-exchange prior to transmission, so you could think about public key encryption.
I am trying to develop a strategy game and i am thinking of creating the following game maps similar to below.
(source: totaldiplomacy.com)
(source: teamteabag.com)
How do i go about doing it and what kind of software to use of books/ tutorials to follow?
Thanks
Assuming that you can draw the graphics that you need, the rest is accomplished by defining the "territories".
A territory will have
a name
a location (just a simple position would probably suffice, one for each place where you want to draw the key bits of information)
a list of neighboring territories
any other game-relevant information, such as what units are there, what resources it provides, etc.
The "hard" bit may be generating the connectivity graph. It's probably easiest to refer to each of your territories by number, as in your second image. Then, the "list of neighboring territories" for territory 14 would be 13, 15, and 23. So don't try to do this automatically, it'll be much easier (as long as the scope doesn't grow too large) to just define this manually.
In the general case, ignoring language and framework, you want to have two things:
a model, which in both those examples would store all the domains, armies, etc.
a map view, which in the simple case is an image file of some kind with some kind of tagging to indicate which bits of the model go where.
If you're looking to program games, I would recommend the XNA framework. There is alot of good resources for new programmers, head over to http://msdn.microsoft.com/en-us/library/bb203893%28v=XNAGameStudio.40%29.aspx to get started on your first game!
I'm trying to estimate the hours required to build a group of 5 simple children's games in Flash. They will include such things as having kids drag and drop healthy food items into a basket; choosing the healthy and unhealthy food items by marking them in some way; etc.
I have no experience building games in Flash, but I have programmed in Flex and Actionscript. How many hours do you estimate for this project?
While your ActionScript background will help, I find Flash to be a VERY different experience from Flex and that proficiency in one environment does not translate well.
Is there a compelling reason not to use Flex? I think you would likely be much more efficient.
That aside, the mechanics of a simple drag and drop game could be put together fairly quickly. There are some good examples of basic drag and drop around. It can be a little tricky to get the mouse coordinates right if it is your first time.
That aside, there are other hidden costs you need to remember. Connecting infrastructure for example. Are the games connected in some way? Is there a running score or persistence that might imply authentication? Is there a story?
Also, If your forte is programming, don't underestimate that challenges of obtaining or creating art and sound assets.
Before you can estimate the time you'll need to break down what the games do. In other words, you'll need to write up very clear and definite requirements. You may even need to write up specifications. Once you've analyzed what the software should do, the estimate will also take a while - one part for example is figuring out whether there's already software that does what you want.
In my opinion, the best way you can possibly estimate a programming project, especially one in a technology you don't understand, would be to apply the Use Case Points methodology. Basically you break the project up into use-cases (what the users are trying to do) and actors (the user types and the system itself) and then list a few team and environment factors (how big an issue is code re-use, how familiar are you with the lanaguage, etc.) Studies have shown that it's more accurate for inexperienced developers than estimating based on features alone.
A google search for "use case points estimate" reveals many useful links. This explanation of the methodology seems to do a good job explaining how it works, though I've not read the entire thing. This worksheet will help when you're ready to start listing points.