Changelog
- Improved performance
- Added edge-detection effect, for better reading experience.
Package URL
http://ppa.dyatkovskiy.com/raspbian/pool/main/b/bird-osd/bird-osd_1.1.2_armhf.deb
How to install?
Please read Installation instructions
http://ppa.dyatkovskiy.com/raspbian/pool/main/b/bird-osd/bird-osd_1.1.2_armhf.deb
Please read Installation instructions
Hi there! I’m working on text rendering for my small Bird OSD project.
So I want to add contours to the text, so it could be visible whatever background it is rendered on (bright or dark).
For example I want to enhance text rendering for cases like this:
(Ugh… My eyes suffer!)
Into this one:
Assuming we have 1-component color on input which consists only of alpha channel, I want to mark as edge alpha values around 0.5.
Below is my shader which works, and in fact above are screenshots with its demonstraction. It still has some limits though. Edge radius can’t take values ended with .5 due to special rounding case for N*0.5 values. If you use it, and find more issues, please let me know.
// The inpute textures uniform sampler2D uTexture; varying vec2 vTexCoord; // Interpolated texture coordinate per fragment. uniform float uOpacity; uniform float uWidth; uniform float uHeight; // If foreground value is higher than threshold, than edge is zero for this pixel const float NO_EDGE_TRESHOLD = 0.5; // Edge radius, works fine in range from 0.6 to 2.0 // Please don't use N*0.5 values, since it has special rounding rules // and pixel at the left may be in is not the same distance comparing to the right. const float EDGE_RADIUS = 1.; const vec3 EDGE = vec3(0., 0., 0.); // Detects whether we should put edge value in the center. // Not that if the center is foreground value = 1, then there is // no need in edge // (in practice we also admit some values below 1, // determined by threshold). // We work with fonts, not the regular image, so // edge is a function from average of two pixels (not the difference): // f(l, r) = edge((l + r) / 2) // assuming edge should be max, when input value is "k" (belongs to range (0, 1) ) // So, how 'edge' function is defined? // (see picture if formulaes are difficult) // edge(v) = (1./k) * x, if x <= k && x > 0 // otherwise it is line which goes through p1[x,y] = [1, k] and p2[x,y] = [0, 1] // // Y ^ // | p[y=1,x=k] // | /\ // | / \ // |/ \ // -----------> // 0 k 1 X // y=edge(x) formulae // // in case when k = 0.5 then // // f(l, r) = 1 - |l + r - 1| // // Let's use this case! // // params: // left - left foreground value // center - center foreground value // right - right foreground value // returns: // edge value. // float getEdge(float left, float center, float right) { if (center > NO_EDGE_TRESHOLD) return 0.; if (center > left && center > right) return 0.; float ledge = 1. - abs(left + center - 1.); float redge = 1. - abs(right + center - 1.); return max(ledge, redge); } float getNeighbour(float row, float col) { float dx = EDGE_RADIUS / uWidth; float dy = EDGE_RADIUS / uHeight; float texX = clamp(vTexCoord.x + col * dx, 0. + dx/2., 1. - dx/2.); float texY = clamp(vTexCoord.y + row * dy, 0. + dx/2., 1. - dx/2.); return texture2D(uTexture, vec2(texX, texY)).a; } float calcEdge(float centerValue) { // Nighbour pixels: // neighbour[i][j] is neighbour with X = x + (j-1) * DX; Y = y + (i-1) * DY; // neighbour[0][0] is neighbour with X = x - DX; Y = y - DY; float neighbour_0[3]; float neighbour_1[3]; float neighbour_2[3]; for (int j = 0; j != 3; ++j) neighbour_0[j] = getNeighbour(-1., float(j-1)); for (int j = 0; j != 3; ++j) neighbour_1[j] = getNeighbour(0., float(j-1)); for (int j = 0; j != 3; ++j) neighbour_2[j] = getNeighbour(1., float(j-1)); float horEdge = getEdge(neighbour_1[0], centerValue, neighbour_1[2]); float vertEdge = getEdge(neighbour_0[1], centerValue, neighbour_2[1]); float ltrbEdge = getEdge(neighbour_0[0], centerValue, neighbour_2[2]); float rtlbEdge = getEdge(neighbour_0[2], centerValue, neighbour_2[0]); return max( max(horEdge, vertEdge), max(ltrbEdge, rtlbEdge) ); } vec4 calcFinalValue(vec3 foreground, float foregroundValue, float edgeValue) { #if 1 float sumFgEdge = foregroundValue + edgeValue; vec3 color = vec3( foreground * foregroundValue / sumFgEdge + EDGE * edgeValue / sumFgEdge); return vec4(color.r, color.g, color.b, min(sumFgEdge, 1. * uOpacity)); //return vec4(EDGE, edgeValue); #else return vec4(foreground.r, foreground.g, foreground.b, foregroundValue); #endif } // The entry point for our fragment shader. void main() { vec4 texColor = texture2D(uTexture, vTexCoord); float foregroundValue = texColor.a; float edgeValue = calcEdge(foregroundValue); gl_FragColor = calcFinalValue( vec3(texColor.r, texColor.g, texColor.b), foregroundValue, edgeValue ); }
You have Raspberry Camera and you need FPV, but you can’t fight 100-200ms latency? Then there is a solution.
Bird OSD turns your Raspberry PI into FPV stream source with OSD overlay.
How?
Since raspberry has Video Composite Output, you can then cast raspberrian screen just like a regular FPV signal over FPV transmitter module!
Raspberry Pi works on broadcomm SoC with VideoCore processor so that means we can apply OSD overlay to camera stream with really low realtime latencies.
Bird OSD is a systemd service, it uses raspivid app to grab camera image, and it uses own bird-osd GLES2 application to apply overlay with sensor data on it.
So finally you should see something like this:
(GPS was broken, sorry, still can’t demonstrate in real fly)
Another pic from FPV goggles:
127.0.0.1:14550
(running ardupilot, arducopter, whatever)Download .deb package onto your raspberry device:
$ wget http://ppa.dyatkovskiy.com/raspbian/pool/main/b/bird-osd/bird-osd_1.1.2_armhf.deb
And then install it:
$ sudo dpkg -i bird-osd_1.1.2_armhf.deb
Then you should target MAVLink channel to 127.0.0.1:14550
E.g. for arducopter:
$ sudo nano /etc/default/arducopter
Ensure you have string like this:
TELEM1="-A udp:127.0.0.1:14550"
Or like this:
TELEM2="-C udp:127.0.0.1:14550"
In case you modified /etc/default/arducopterconfig, then you should restart service:
$ sudo systemctl restart arducopter
Finally you should start bird-osdservice with this command:
sudo systemctl start bird-osd
Then on monitor connected to your raspberryyou should see whatever your camera sees + overlay with sensors data!
It is still very first version:
libraspberrypi-bin (>= 1.20180417-1), bash (>= 4.4-5)
Perhaps dependency versions are higher then it really needs, just had no opportunity to test it on another envs.
If you want to enable bird-osdon boot, you should run:
$ sudo systemctl enable bird-osd
This command disables service:
$ sudo systemctl disable bird-osd
And this command removes bird-osdfrom you raspberry device:
$ dpkg -P bird-osd
Edge detection for text – simple edge detection shader for text-like foreground drawings