We are implementing a delegate-MAS solution where intention, feasibility and exploration ants are depicted by Messages in a CommsModel (as suggested here). We would like to track the path these messages have followed through the model, by adding their location to a Queue every tick. We cannot find a way to retrieve their position however. Is there a method for this we can use? Do we need to add messages as roadusers to the roadmodel?
If you are implementing the ants as MessageContents using a CommModel then these 'ants' do not have a position and are not added to a model. They are just regular Java objects. In this case, you'll have to implement any position tracking yourself.
If you are implementing the ants as a CommUser then they are message senders and may have a position. Keeping track of the position can then be implemented by requesting the position at every tick.
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I am using opencv and openvino and am trying to figure out when I have a face detected, use the cv2.rectangle and have my coordinates sent but only on the first person bounded by the box so it can move the motors because when it sees multiple people it sends multiple coordinates and thus causing the servo and stepper motors to go crazy. Any help would be appreciated. Thank you
Generally, each code would run line by line. You'll need to create a proper function for each scenario so that the data could be handled and processed properly. In short, you'll need to implement error handling and data handling (probably more than these, depending on your software/hardware design). If you are trying to implement multiple threads of executions at the same time, it is better to use multithreading.
Besides, you are using 2 types of motors. Simply taking in all data is inefficient and prone to cause missing data. You'll need to be clear about what servo motor and stepper motor tasks are, the relations between coordinates, who will trigger what, if something fails or some sequence is missing then do task X, etc.
For example, the sequence of Data A should produce Result A but it is halted halfway because Data B went into the buffer and interfered with Result A and at the same time screwed Result B which was anticipated to happen. (This is what happened in your program)
It's good to review and design your whole process by creating a coding flowchart (a diagram that represents an algorithm). It will give you a clear idea of what should happen for each sequence of code. Then, design a proper handler for each situation.
Can you share more insights of your (pseudo-)code, please?
It sounds easy - you trigger a face-detection inference-request and you get a list/vector with all detected faces (the region-of-interest for each detected face) (including false-positive and false-positives, requiring some consistency-checks to filter those).
If you are interested in the first detected face only - then it could be to just process the first returned result from the list/vector.
However, you will see that sometimes the order of results might change, i.e. when 2 faces A and B were detected, in the next run it could still return faces, but B first and then A.
You could add object-tracking on top of face-detection to make sure you always process the same face.
(But even that could fail sometimes)
I'm trying to do trajectory optimization for a custom robot I've specified with an sdf file.
I'd like to use direct collocation, but when I try to create the MultibodyPlant with time_step=0.0 I fail with a segfault. It works just fine when I use discrete time (e.g. Multibodyplant(time_step=.005).
However, if I use discrete time, the state is no longer continuous so I can't use direct collocation. So I tried to use direct transcription and I get the error
SystemExit: Failure at bazel-out/k8-opt/bin/systems/framework/_virtual_includes/context/drake/systems/framework/context.h:111 in num_total_states(): condition 'num_abstract_states() == 0' failed.
I think the reason is that DirectTranscription does not have a assume_non_continuous_states_are_fixed, the same issue as in this question: direct transcription for compass gait. So maybe the easiest solution to my problem is to request this feature..
I recommended above that we do add that assume_non_continuous_states_are_fixed to DirectTranscription. But the reason that this option was not implemented already is a little subtle, so I’ll add it here.
It’s not actually MultibodyPlant that is adding the abstract state, but SceneGraph. For dynamics/planning, you only need SceneGraph if you are relying on contact forces in your dynamics. For acrobots / cart-poles, etc, you can already use a MultibodyPlant with DirectTranscription by passing the MBP only (no SceneGraph) to the optimization. And for systems that do make and break contact, I would have said that DirectTranscription might not be the algorithm you want; although there are no hard and fast rules saying it won’t work. It’s just that you’ll end up with stiff differential equations which are hard to transcribe in a reasonable trajectory optimization that doesn’t reason explicitly about the contact.
I think I know your application, which involves wheels that are in contact and stay in contact. That means that you do need SceneGraph. That might be a case were this currently missing combination makes perfect sense, and we should add it.
I have a channel that I want stop animations from happening if running on a slower device like Roku Express and keep them on a faster device like Roku Premiere. Except I'm not sure what's the best way to go about it.
I wanted to filter by the amount of available ram, but I couldn't find an api that gives me available ram for the system that I could run in my code.
I could filter by model name, but I would then need to keep an update list of model names, which I prefer not to do.
Any help/insight appreciated.
Re graphic capabilities, try roDeviceInfo.getGraphicsPlatform() - if it returns opengl, that high performing engine that can do arbitrary rotations vs directfb being limited.
Re CPU, you can run a mini benchmark on start of your program, something like
ti = createObject("roTimeSpan"): s=""
for i = 1 to 1000: s = s + right((i^3).toStr(),2): end for
time = ti.totalMilliSeconds()
Have you considered using Animation.optional=true?
It won't stop them from happening on Roku Express (since it is a Littlefield) but it will "skip animations on lower performing Roku devices (Paolo, Giga, Jackson, Tyler, and Sugarland)".
Animation also contains an undocumented field called "willBeSkipped" which will be true on slower devices when "optional" is set to true.
I had the similar problem with the animations. Unfortunately, You must filter by model name. I didn't find another way.
You can store the list of devices in database so it would be easier for You to maintain.
You can set the optional field on the animation node to true. This is supposed to take care of that. I have set this field to true before and it does not seem to have an effect. I'm sure they'll get around to fixing it eventually.
The efficiency of the animations also depends on how many animation nodes you have. You should only need 1 animation node to handle all of your animations for a particular component. Add an interpolator for each individual type of animation you want to occur (i.e. scaling, rotating, color-shifting, translating).
I am looking for a method that redraws all the features stored in a layer (equivalent to method "redraw" with OL2)
the method "changed" of class ol.layer.Vector "refreshes" only the features visible on a map (for instance in the zoomed part)
and thus doesn't impact the features outside
the treatment applied to those data is to delete periodically old features
how can I achieve this ?
another question is how to be notified of the end of this specific deletion ?
thanks in advance
Jean-Marie
first thanks for your answers
my question requires effectively more information :
the browser client receives points through a real time websocket connection
every second, an array of new features collected from those points is added into the Vector layer in this way :
vectorLayer.getSource().addFeatures(features);
the duration of the source buffer is, for instance one hour, and to manage a temporal sliding window of one hour, old features are removed every minute
map.once('postrender',removeOldFeatures);
vectorLayer.changed(); or map.renderSync();
this removal is only correctly done for visible features
But as soon as some features are not visible due, for instance, to a zoom on a portion of the map where those features are not displayed, then the removal treatment (removeOldFeatures) is not executed for those features whatever the method used (vectorLayer.changed() or map.render())
as a consequence the number of features doesn't stop increasing...
Jean-Marie
I had the same problem with a TileVector Source and format GeoJSON. At the end i use the provided TileUrlFunction and to redraw the layer, i just set the Source again with the layer.setSource(yourdefinedSource) method. Dube is right. Most of the time (if the source is updated to often) it is useful to send a unique param (like unix timestamp) as a cachebuster.
I am developing a location-based application in which I need to get nearby location name of any geopoint selected by user. I'm using Google Places API which is working fine for me.
Only problem is the service returns null for geopoints in water. Is there any way that I can retrieve nearby locations for a geopoint in water or ocean?
AFAIK the API has no way to do that.
So, you've got two options, in order of the effort it takes:
When user taps water just throw a dialog saying "Please select a
point on land". Next to no effort and will slightly annoy the user.
Try to find the closest land geopoint yourself and use it to run the API request on
(instead of the original point). Below are some ideas on that.
A good approach can be based on this answer: basically you can get a KML file with land polygons. For performance reasons, you can simplify the polygons to the extent that makes sense for your zoom levels. Now if your point is in one of those polygons -- it's sea. And you can simply iterate over all polygon edges and pick the one that's closest to your point, then pick a point on it - again closest to your point - and do one little epsilon-sized step towards the outside of the polygon to get a land point you can do a geocode request on. Also, the original author suggests you can use Haversine formula to determine neares land point -- I'm not really familiar with the appliance of that one.
The downside is, you have to deal with KML, iterate over a lot of polygons and optimize them (and lose precision doing that, in addition to possible differences between marineregions.org data and Google Places data)
Another cool trick you could try is using Sobel Filter [edge detection] on the visible map fragment to determine where coastline is (although you will get some false positives there), then trace it (as in raster->vector) to get some points and edges to calculate the closest land position with, in a manner similar to the former approach. Here's a clumsy drawing of the idea
For Sobel edge detection, consider GPUImage lib -- they have the filter implemented and it's probably going to work crazy fast since the lib does all the calculations on GPU.
UPD Turns out there's also a service called Koordinates that has coastline data available, check the answer here