When clicking on a marker, I would like to zoom my map enough to distinguish it from the other markers around it.
My marker is 10x10 pixels.
Distance to the nearest marker is 0.02km.
I would like a margin of 5 pixels between them.
How could I compute the required zoom based on those parameters ?
Thanks !
Related
I'm trying to programatically "draw" a circle with multiple Marker with React leaflet.
I'm doing it with cosinus and sinus trying to calculate theirs coordinate from the center point ...
But the more I'm near the pole the more the circle is an ellipssis ... Is it a way to transform the calculus to take this into account ?
In this example I'm in Oulu (near the pole) If you just change the x var into '0' you'll notice that the markers are now in circle !
please see this CodePen
Because a Leaflet map is a projection of a sphere onto a flat map, distortions will happen near the poles. You want to project your spherical Lat/Lng into flat Points, calculate the marker placements in flat Points and then unproject the points back to spherical LatLng.
I have to display the Earth's map in azimuthal equidistant projection, by giving the lattitude and longnitude as input in Matlab. I am using the eqdazim projection, but I am still getting the map with point (0,0) in the center. I want to be able to change the point that is the center if the circle map.
landareas = shaperead('landareas.shp','UseGeoCoords',true);
axesm ('eqdazim', 'Frame', 'on');
geoshow(landareas);
Also, I don't know how to change the radius of the image. I don't need the circle with the whole Earth but instead something about ~2000km radius around center point.
I need it in order to put its image on a dome. Below is a simple example with such a dome and random fragment of the Earth's surface. Keep in mind, that it's just an image that I cropped manually from large Mercator map.
I was hoping that I can use the Mapping Toolbox in order to get such a map automatically, by giving lattitude, longnitude and radius. I have all necessary data, which is:
Lattitude & Longnitude
The radius of the circle
I just don't know how can I get this part of Earth's map. I think I have to use the azimuthal equidistant projection. I just don't know how to do this in MATLAB/Mapping Toolbox.
I'm trying to find a way to rotate an arbitrary polygon around its own geometric center. It was drawn in a blackboard built with creating js.
I've been trying many approaches, but any of them has worked.
How can I accomplish it?
Find the geometric centre as the average of all the points' coordinates. Make all the points relative to this centre (such that the centre is (0,0)), then rotate them by the desired angle using a rotation matrix. You can then draw using these points.
This is assuming you have the coordinates of all the points.
I have a system of finite size circular particles (say r=5cm) which I need to plot in a given domain (say L=5m). Since they are many, scatter is faster than any cyclic use of rectangle.
What is unclear to me is the correct way to define the diameter/radius of the circles/marker so to scale correctly with the domain geometry which is plotted as well. (By using rectangle, the diameter of the particle can be easily defined.)
Based on this answer, it is possible to have fine control of the marker size, although the real scaling is obscure to me.
Can anyone shed some light?
The SCATTER function expects its 'S' parameter to contain the marker
area in points squared. This area corresponds to the area of a square
bounding box around the marker.
The source is the technical solution "How do I specify the size of the markers created by the SCATTER plot in units proportional to the data being plotted in MATLAB 7.6 (R2008a)?"
Check out the code in the link.
The official documentation states:
MarkerSize
Marker size. Size of the marker in points. The default value is 6.
Note that one point is 1/72 of an inch, so it's an absolute measurement unit.
If you want to tune the marker sizes according to the axis scale of your plot, do a simple unit conversion: calibrate 1 tick in one of the axes to points (you can do it by trial and error), and then normalize all your marker sizes by it (it doesn't, however, occur to me how you'd keep the marker sizes relative to the plot's zoom level in a straightforward manner).
By the way, you can specify the sizes of the markers directly as the third parameter in the scatter command. With this, you can avoid the get and set manipulations mentioned in the answer to which have linked your question.
I am currently doing a project called eye controlled cursor using MATLAB.
I have few stages before I extract out the center of the iris (which can be considered as a pupil location). face detetcion - > eye detection -- > iris detection -->And finally i have obtained the center of the iris as show in the figure.
Now, I am trying to map this position (X,Y) to my computer screen pixel (1366 x 768). In most of the journals I have found, they require a reference point such as lips, nose or eye corner. But I am only able to extract the center of iris by doing certain thresholding. How can i map this position (X,Y) to my computer screen pixel (1366 x 768)?
Well you either have to fix the head to a certain position (which isn't very practical) or you will have to adapt to the face position. Depending on your image, you will have to choose points that are always on that image and are easy to detect. If you just have one point (like the nose), you can only adjust for the x/y shift of your head. If you have more points (like the 4 corners of the eye, the nose, maybe the corners of the mouth), you can also extract the 3 rotational values of the head and therefore calculate the direction of sight much better. For a first approach, I guess only the two inner corners of the eye (they are "easy" to detect) will do.
I would also recommend using a calibration sequency. You present the user with a sequence of 4 red points in the corners of the screen and he has to look at them. You can then record the positions of the pupils and interpolate between them.