I have a grid where I'm using one sf:RectangleShape object and with changing parameters of it inside a loop I can populate a wide area with them. Now I want to make grid visible to assist with placing Rectangles.
But here comes the issue.
If I will use rectPtr->getRect()->setOutlineThickness(-0.5f); Note: Its pointer created from custome class. From unknown reasons final program becomes really slow and unstable. Its running just fine with setOutlineThickness(0.f);. Im using negative value because of that grid, but there is no problem,. it do same with positive values.
Is there some way to use setOutlineThickness(); function without slowing the program?
May it be some kind of bug?
I'm using sf::Transform 3x3 matrix at window.draw(), could be there some violation?
average FPS with setOutlineThickness(-1.f) = 16.fps
average FPS with setOutlineThickness(0.f) = 60.fps
many thanks
Related
So this question has been asked a few times, but I think my C++ skills are too deficient to really appreciate the answers. What I need is a way to start with an HEVC encoded video and end with CSV that has all the motion vectors. So far, I've compiled and run the reference decoder, everything seems to be working fine. I'm not sure if this matters, but I'm interested in the motion vectors as a convenient way to analyze motion in a video. My plan at first is to average the MVs in each frame to just get a value expressing something about the average amount of movement in that frame.
The discussion here tells me about the TComDataCU class methods I need to interact with to get the MVs and talks about how to iterate over CTUs. But I still don't really understand the following:
1) what information is returned by these MV methods and in what format? With my limited knowledge, I assume that there are going to be something like 7 values associated with the MV: the frame number, an index identifying a macroblock in that frame, the size of the macroblock, the x coordinate of the macroblock (probably the top left corner?), the y coordinate of the macroblock, the x coordinate of the vector, and the y coordinate of the vector.
2) where in the code do I need to put new statements that save the data? I thought there must be some spot in TComDataCU.cpp where I can put lines in that print the data I want to a file, but I'm confused when the values are actually determined and what they are. The variable declarations look like this:
// create motion vector fields
m_pCtuAboveLeft = NULL;
m_pCtuAboveRight = NULL;
m_pCtuAbove = NULL;
m_pCtuLeft = NULL;
But I can't make much sense of those names. AboveLeft, AboveRight, Above, and Left seem like an asymmetric mix of directions?
Any help would be great! I think I would most benefit from seeing some example code. An explanation of the variables I need to pay attention to would also be very helpful.
At TEncSlice.cpp, you can access every CTU in loop
for( UInt ctuTsAddr = startCtuTsAddr; ctuTsAddr < boundingCtuTsAddr; ++ctuTsAddr )
then you can choose exact CTU by using address of CTU.
pCtu(TComDataCU class)->getCtuRsAddr().
After that,
pCtu->getCUMvField()
will return CTU's motion vector field. You can extract MV of CTU in that object.
For example,
TComMvField->getMv(g_auiRasterToZscan[y * 16 + x])->getHor()
returns specific 4x4 block MV's Horizontal element.
You can save these data after m_pcCuEncoder->compressCtu( pCtu ) because compressCtu determines all data of CTU such as CU partition and motion estimation, etc.
I hope this information helps you and other people!
I'm using OpenCV 3.3.1. I want to do a semi-dense optical flow operation using cv::calcOpticalFlowPyrLK, but I've been getting some really noticeable slowdown whenever my ROI is pretty big (Partly due to the fact that I am letting the user decide what the winSize should be, ranging from from 10 to 100). Anyways, it seems like cv::buildOpticalFlowPyramid can mitigate the slowdown by building image pyramids? I'm sorta familiar what image pyramids are, but in context of the function, I'm especially confused about what parameters I pass in, and how it impacts my function call to cv::calcOpticalFlowPyrLK. With that in mind, I now have these set of questions:
The output is, according to the documentation, is an OutputArrayOfArrays, which I take it can be a vector of cv::Mat objects. If so, what do I pass in to cv::calcOpticalFlowPyrLK for prevImg and nextImg (assuming that I need to make image pyramids for both)?
According to the docs for cv::buildOpticalFlowPyramid, you need to pass in a winSize parameter in order to calculate required padding for pyramid levels. If so, do you pass in the same winSize value when you eventually call cv::calcOpticalFlowPyrLK?
What exactly are the arguments for pyrBorder and derivBorder doing?
Lastly, and apologies if it sounds newbish, but what is the purpose of this function? I always assumed that cv::calcOpticalFlowPyrLK internally builds the image pyramids. Is it just to speed up the optical flow operation?
I hope my questions were clear, I'm still very new to OpenCV, and computer vision, but this topic is very interesting.
Thank you for your time.
EDIT:
I used the function to see if my guess was correct, so far it has worked, but I've seen no noticeable speed up. Below is how I used it:
// Building pyramids
int maxLvl = 3;
maxLvl = cv::buildOpticalFlowPyramid(imgPrev, imPyr1, cv::Size(searchSize, searchSize), maxLvl, true);
maxLvl = cv::buildOpticalFlowPyramid(tmpImg, imPyr2, cv::Size(searchSize, searchSize), maxLvl, true);
// LK optical flow call
cv::calcOpticalFlowPyrLK(imPyr1, imPyr2, currentPoints, nextPts, status, err,
cv::Size(searchSize, searchSize), maxLvl, termCrit, 0, 0.00001);
So now I'm wondering what's the purpose of preparing the image pyramids if calcOpticalFlowPyrLK does it internally?
So the point of your question is that you are trying to improve speed of optical flow tracking by tuning your input parameters.
If you want dirty and quick answer then here it is
KTL (OpenCV's calcOpticalFlowPyrLK) define a e residual function which are sum of gradient of point inside search window .
The main purpose is to find vector of point that can minimize residual function
So if you increase search window size (winSize) then it is more difficult to find that set of points.
If your really really want to do that then please read the official paper.
See the section 2.4
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.185.585&rep=rep1&type=pdf
I took it from official document
https://docs.opencv.org/2.4/modules/video/doc/motion_analysis_and_object_tracking.html#bouguet00
Hope that help
I am using BackgroundSubtractorMOG in OpenCV to track objects. When they appear, it works fine but the background fastly adapts so I cannot track static objects. How can I make the background adaptation slower (I dont want it fully static, just slower)?
Setting the learning rate using the constructor doesn't change that:
BackgroundSubtractorMOG pBSMOG = BackgroundSubtractorMOG(???);
How can I solve this? Thanks!
BackgroundSubtractorMOG pBSMOG = BackgroundSubtractorMOG(int history=200, int nmixtures=5, double backgroundRatio=0.7, double noiseSigma=0);
Where,
history – Length of the history.
nmixtures – Number of Gaussian mixtures.
backgroundRatio – Background ratio.
noiseSigma – Noise strength (standard deviation of the brightness or each color channel). 0 means some automatic value.
Increasing the history value will slow down the adaptation rate.
There is another function available in OpenCV:
Ptr <BackgroundSubtractorMOG2> createBackgroundSubtractorMOG2(int
history=500, double varThreshold=16, bool detectShadows=true )
This is much faster than the previous one and it can eleminate detecting shadows too.
I have an array - 2D(100 x 100 in this case) with some states limited within borders as shown on picture:
http://tinypic.com/view.php?pic=mimiw5&s=5#.UkK8WIamiBI
Each cell has its own id(color, for example green is id=1) and flag isBorder(marked as white on pic if true). What I am trying to do is exclude set of cell with one state limited with borders(Grain) so i could work on each grain separately which means i would need to store all indexes for each grain.
Any one got an idea how to solve it?
Now that I've read your question again... The algorithm is essentially the same as filling the contiguous area with color. The most common way to do it is a BFS algorithm.
Simply start within some point you are sure lays inside the current area, then gradually move in every direction, selecting traversed fields and putting them into a vector.
// Edit: A bunch of other insights, made before I understood the question.
I can possibly imagine an algorithm working like this:
vector<2dCoord> result = data.filter(DataType::Green);
for (2dCoord in result) {
// do some operations on data[2dCoord]
}
The implementation of filter in a simple unoptimized way would be to scan the whole array and push_back matching fields to the vector.
If you shall need more complicated queries, lazily-evaluated proxy objects can work miracles:
data.filter(DataType::Green)
.filter_having_neighbours(DataType::Red)
.closest(/*first*/ 100, /*from*/ 2dCoord(x,y))
.apply([](DataField& field) {
// processing here
});
I'm new to C++ and DirectX, I come from XNA.
I have developed a game like Fly The Copter.
What i've done is created a class named Wall.
While the game is running I draw all the walls.
In XNA I stored the walls in a ArrayList and in C++ I've used vector.
In XNA the game just runs fast and in C++ really slow.
Here's the C++ code:
void GameScreen::Update()
{
//Update Walls
int len = walls.size();
for(int i = wallsPassed; i < len; i++)
{
walls.at(i).Update();
if (walls.at(i).pos.x <= -40)
wallsPassed += 2;
}
}
void GameScreen::Draw()
{
//Draw Walls
int len = walls.size();
for(int i = wallsPassed; i < len; i++)
{
if (walls.at(i).pos.x < 1280)
walls.at(i).Draw();
else
break;
}
}
In the Update method I decrease the X value by 4.
In the Draw method I call sprite->Draw (Direct3DXSprite).
That the only codes that runs in the game loop.
I know this is a bad code, if you have an idea to improve it please help.
Thanks and sorry about my english.
Try replacing all occurrences of at() with the [] operator. For example:
walls[i].Draw();
and then turn on all optimisations. Both [] and at() are function calls - to get the maximum performance you need to make sure that they are inlined, which is what upping the optimisation level will do.
You can also do some minimal caching of a wall object - for example:
for(int i = wallsPassed; i < len; i++)
{
Wall & w = walls[i];
w.Update();
if (w.pos.x <= -40)
wallsPassed += 2;
}
Try to narrow the cause of the performance problem (also termed profiling). I would try drawing only one object while continue updating all the objects. If its suddenly faster, then its a DirectX drawing problem.
Otherwise try drawing all the objects, but updating only one wall. If its faster then your update() function may be too expensive.
How fast is 'fast'?
How slow is'really slow'?
How many sprites are you drawing?
How big is each one as an image file, and in pixels drawn on-screen?
How does performance scale (in XNA/C++) as you change the number of sprites drawn?
What difference do you get if you draw without updating, or vice versa
Maybe you just have forgotten to turn on release mode :) I had some problems with it in the past - I thought my code was very slow because of debug mode. If it's not it, you can have a problem with rendering part, or with huge count of objects. The code you provided looks good...
Have you tried multiple buffers (a.k.a. Double Buffering) for the bitmaps?
The typical scenario is to draw in one buffer, then while the first buffer is copied to the screen, draw in a second buffer.
Another technique is to have a huge "logical" screen in memory. The portion draw in the physical display is a viewport or view into a small area in the logical screen. Moving the background (or screen) just requires a copy on the part of the graphics processor.
You can aid batching of sprite draw calls. Presumably Your draw call calls your only instance of ID3DXSprite::Draw with the relevant parameters.
You can get much improved performance by doing a call to ID3DXSprite::Begin (with the D3DXSPRITE_SORT_TEXTURE flag set) and then calling ID3DXSprite::End when you've done all your rendering. ID3DXSprite will then sort all your sprite calls by texture to decrease the number of texture switches and batch the relevant calls together. This will improve performance massively.
Its difficult to say more, however, without seeing the internals of your Update and Draw calls. The above is only a guess ...
To draw every single wall with a different draw call is a bad idea. Try to batch the data into a single vertex buffer/index buffer and send them into a single draw. That's a more sane idea.
Anyway for getting an idea of WHY it goes slowly try with some CPU and GPU (PerfHud, Intel GPA, etc...) to know first of all WHAT's the bottleneck (if the CPU or the GPU). And then you can fight to alleviate the problem.
The lookups into your list of walls are unlikely to be the source of your slowdown. The cost of drawing objects in 3D will typically be the limiting factor.
The important parts are your draw code, the flags you used to create the DirectX device, and the flags you use to create your textures. My stab in the dark... check that you initialize the device as HAL (hardware 3d) rather than REF (software 3d).
Also, how many sprites are you drawing? Each draw call has a fair amount of overhead. If you make more than couple-hundred per frame, that will be your limiting factor.