I'm doing a robot navigation and path planning project based on simulating the turtlebot3 and driving with the A* planner.
I'm using a program that allows the robot to plan a route only through 'cells' with no cost value (aka. freespace with an inflation cost of 0). However, adjusting the inflation radius I'm experiencing that the robot either cannot pass through narrow openings when the inflation is higher, but drive along a wall when it is low.
I'm wondering if there is a way to control the inflation or something? My desires outcome is for the robot to drive in the center of wide hallways, not along walls, but be able to pass through doors that it should be able to fit through.
Thank you.
I managed to solve this problem thanks to some advice that made me look outside the box.
The problem was intrinsic to my planner, the fact that allowed space to navigate through was binary (aka. either perfectly allowed to drive through or not allowed).
Instead I changed it so that all space other than the walls were allowed space, and added the cost of a cell (from the cost map) to the cells. That way instead of being binary whether the drive can or can't drive in a cell, both the distance and cost of the cells affect the robots path, making it try to keep away from walls, but able to pass through places of high cost if there's no other way.
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In ARKit for iOS. If you display a virtual item then it always comes before any real item. This means if I stand in front of the virtual item then I would still see the virtual item. How can I fix this scenario?
The bottle should be visible but it is cutting off.
You cannot achieve this with ARkit only. It offers no off the shelve solution for solving occlusion, which is a hard problem.
Ideally you'd know the depth of each pixel projected on the camera, and would use that to determine those that are in front and those that are behind. I would not try something with the feature points ARKit is exposing since 1) their position is innacurate 2) there's no way to know between two frames which feature point of frame A is which feature point in frame B. It's way to noisy data to do anything good.
You might be able to achieve something with third party options that'd process the captured image and understand depth or different depth levels in the scene, but I don't know any good solution. There's some SLAM technique that yields dense depth map like DTAM (https://www.kudan.eu/kudan-news/different-types-visual-slam-systems/) but that'd be redoing most of what arkit is doing. There might be other approaches that I'm not aware off. Apps like snap do this in their own way so it is possible!
So basically your question is to mapping the coordinate of the virtual item on real world coordinate system, in short, you want to see the virtual item blocked by the real item, and you can only see the virtual item once you pass the real item.
If so, you need to know the physical relations of each object in this environment, and then you need to know exactly where you are to decide if the virtual item is blocked.
It's not an intuitive way to fix this, however, it's the only way I can think of.
Cheers.
What you are trying to achieve is not easy.
You need to detect the parts of the real world that "should be visible" using some kind of image processing. Or maybe the ARKit feature points that have the depth information, then based on this you have to add "an invisible virtual object" that cuts the drawing of things behind it. This will represent your "real object" inside the "virtual world" so that the background (camera feed) remains visible in places where this invisible virtual object is present.
Ok, I've done some reading around the subject, have an idea of how I'd tackle my problem, but want to find out of this is the most efficient way, or if I'm missing something simple.
I have a line diagram of a section of railway that I'd like to plot the users location onto (the user being someone on a train moving up/down the railway).
Now, I initially went down the route of geo-referencing, but quickly realised this probably wasn't the way to go, as my image is not a real reflection of the area + I want the line diagram to be what the user sees.
OK, my though process of how I will tackle it:
I know the physical area so I could extract the coordinates along the railway, every x meters (my line diagram has a resolution of around 5m). Stick this into an array. Can anyone suggest a tool to do this?!
Allocate my line diagram a start and end, then match the image coordinates with the physical coordinates for the entire line.
Read in the users position and update where to draw the position based on the closest match in the array?
Does this sound doable, and would it give me decent results?
If you have more sophisticated answers, please do share.
It sounds reasonable in general. As the user is supposed to be on a train a simpler option may work where you just keep track of the physical distance moved and use that as a percentage distance along the line. This is a lot simpler to manage and could be backed up with some coordinate checkpoints to ensure you don't have a drifting error. I'd aim for a simpler implementation if you can.
I have a requirement mentioned below:
Already have a floor plan map image
First detect current location on floor
Then select the destination location using floor plan map image
Now application should provide direction & distance for that source to destination path
This is like how google direction works, but its in-house map require.
For example,
- Current position of user is: At his desk
- Where is Meeting Room #11
- So application should provide direction and distance updates on the map/floor plan image.
Any kind of suggestions/help would be great.
Thanks in advance
Couple of points...
You could create various audio files and play them as way points based on routing. Same principal as 'turn right at the next light'.
Definitely want to set your accuracy to: kCLLocationAccuracyBest. But this will still probably only get you accuracy of around +/- 10 meters at best.
Do a floor plan overlay using MapOverlayView.
If you are indoor, iPhone uses cell towers or WIFI for a location fix. This might be a problem for you because if you are looking to map multiple floors, only GPS can give you altitude readings - ground floor, second floor, etc...
I don't want to pour cold water on your idea but I have not heard of anyone successfully doing an indoor navigation app on an iPhone using standard stuff. If you really wanted to move forward on this project, your best accuracy might be using indoor bluetooth transmitters as navigational beacons...?
What you want is path-planing in the map, is that? If so, there is lot of algoritms you can use. You can choose a block size based on your map and resolution needs, divide de map into this, amd mark each block as navegable or not. Then getting from the first block trying in the direction of the destionation block, check if the neighboor block is blocked or not, and get going, until you reach (or not, if its not reacheable) the destination block.
Thats a pseudo-implementation, you have some option to do it, if I understand your needs.
(I dont know your hardware as said by others, with simple GPS and indoor navigation, assuming a 15m resolution is a good balance between optimistic/pesimistc signal, If its for robot-navigation, its not a goos approach in the GPS terms, but the algorimt is).
I see some ways to do it:
1) Draw using OpenGL programmatically.
2) Draw using QuartzCore and CoreAnimation programmatically.
3) Draw map in AutoCad and then somehow connect it to iOS.
4) Draw map using SVG.
Requirments are supporting pathfinding and gps navigation.
For first 2 ways I think that it's expensive in terms of performance way, redraw all elements on scaling; and I don't think that this way may have GPS-navigation support.
Using AutoCad pictured maps is hard to understand for me how to connect it with graphs\paths for pathfinding.
My colleagues will develop this app on web using SVG. I found it - https://github.com/SVGKit/SVGKit , but still have no idea how it will support pathfinding and navigation.
I would appreciate any help.
Generally there are two types of map application:
A) They display a map, (with or without a user position) without needing to calculate a path like a navigation system does (see point B)
B) Application that use the vectors of a map and calculate something: e.g to find a best path. The shortest connection, e.g A navighation system , etc.
Application for A) are usually less complex then that of B), because the vectors can be somewhat inacurate, have no conections, have small gaps, have no logic between the edges, etc.
1) To only display a building map, you would only need a list of edges. (An edge is pair of coordinates (x1,y1) - (x2,y2). How ever you get that. E.g MapInfo Professional format mif/mid.
Or even you could dispaly a pdf that contains the map of the builing. Right with the built in PDF View, (also with SVG but more difficult).
Things get much more complicated if it is not a relative map, but also a map that is positioned with an reference coordinate system, like latitude/longitude (WGS84).
In that case you would use a Tool (mapInfoProfessional, to import AutoCad DXF Files, and apply 3 GPS measured reference points at the corner of the house, and convert that to LatLong WGS84 coordinates system.
With ios you cannot measure that 3 Points because you cannot average a position, ios stops sending when you are standing still at one corner of the house.
You could try to extract the positions from a google earth satellite foto if you are living in a region where google Sattelite fotos have high resolution. (But this might violate the license conditions of that Satellite Foto provider (Topic: derived data))
Finally you now have a list of edges in Lat Lon coordinate System.
For Displaying I personally would either do with 1) OpenGL) or 2) Quartz2D.
Now the Path finding part.
Probaly you need a second "map" that defines the possible paths inside the building.
This structure must be a connect graph (points with connected neighbours).
Computer games do it that way. (Some even allow you to display that path in developper mode)
The path can be drawn, in a different layer of the floor plan. But this path
has higher requirements: No gaps are allowed, all must be perfect connected.
Call that layer "Path" and export it as own plan.
Now use only this path layer, and import, and create a graph of nodes with connect neighbours.
Use Dijkstra Algo to search for shortest path.
I am developing an app that uses the user's location to be displayed on a map with other users.
I want to ensure that all users have a bit of privacy when it comes to their location being displayed openly to other users, so I am hoping to just set their location with a specified offset (lets say 1 mile) and display the "edited" location to all other users while still showing the "exact" location to the current user.
Example - If I am looking at the map, I want my "user location" (the blue dot) to be somewhat exact, while all other player's will see my location slightly offset from the real location.
What is the best way to achieve this?
I think the question you actually want the answer to is this:
How do I convert the user's location into an "approximate location" in a way that preserves the user's privacy?
It's not an easy problem:
Offsetting by a specific distance doesn't work:
There's a trivial attack if the direction is fixed.
If the direction does not change often enough, then the attacker only needs to wait to identify what looks like a road.
If the direction changes too often, then they'll tend to form a 1-mile circle around the target's house/work.
Offsetting by a random distance/direction doesn't work; the attacker just needs to collect enough samples; the clusters will likely be centered on the target's home/work.
Quantizing to a grid naively (e.g. "X is within this grid square") will tell you when the target crosses a grid boundary. This is especially bad if the target lives on a grid boundary.
Here's something that works a little better, but wil still (eventually) give away the user's location:
Pick an (approximately) 1-mile grid. For a "square" grid, you could use the Pierce quincunxal projection (there are four points of infinite distortion but you can make those all at sea — it looks like you can limit distortion on land to a factor of 2). There are also projections onto cube and, for a triangular grid, an icosahedron.
When you first need to report the user's location, give the nearest point on the grid. Also pick a threshold distance between 1 and 2 grid "squares", or so.
While the user is within the threshold distance of the center of the grid square, continue to report the same grid square. Otherwise, repeat.
It'll still eventually be obvious if the user happens to live on a grid boundary. There are various ways to attempt to fix this problem (e.g. a bias to reporting grid squares you've reported before), but these will eventually fail.
This seems a lot like trying to remove a digital watermark (the user's actual location) by using lossy compression (the approximation process) while producing an output image/audio (approximate location) that sounds/looks like the original. (The analogy works a little better if you treat the "watermark" as the user's daily habits, which will be visible in the output unless you know exactly what those habits are and can remove them.)
Or in signal processing terms: A low SNR simply means you have to listen for longer to extract the signal.
Are you showing everyone else as a pin? It might be strange if you show a pin at an exact location but the other user isn't there. For example if someone was a mile north and you showed their pin at the same location as the current user. Maybe you should display the other users with an MKOVerlay circle, and then use some calculation base on a userID to shift it slightly off centre so that people don't find out that it is always shifted 500m east and thus easily see here people are.
Whether or not you change the display, the code you seek is here: Get the GPS coordinate given the current location, bearing and distance