I want to use a Makefile to produce lots of images by script in the same manner as TeX tikz. It can be a different script language, but it should be either simple or worth the extra power.
I use graphviz and gnuplot and love them both. Both are driven by text scripts describing what is to be drawn. Absolutely no GUI should be necessary.
The script should be able to do the usual things like drawing a red line.
draw[line width=2px,color=red] (0,0,0) -- (1,1,1);
Are there any good choices for script-driven 3D image generating programs with the look and feel of graphviz or gnuplot?
Related
I want to determine if a laser dot (or dots) are anywhere in the field of view of my camera. I can flash the laser in synchronization with the camera frames so the dots are present only on alternate frames. This method should give 100% confidence that any visible dots are from my laser after processing 4 or 5 frames.
My first project involves determining if the laser dot (or dots) are visible at all, and the second project would be to determine the pixel separation (H and V) of two or more dots.
I would like to be able to run the software on a Raspberry pi.
Does anyone have any experience doing something like this? Would anyone be interested in helping me accomplish these projects?
I dont get why you got downvotes...
Yes, you are able to realize this. Depending on your programming skills, i would choose python or C++. Following stuff is pretty simple but only works if your camera isnt moving. The Keyword is: Differenceimage
Algorithm
You could simply do some difference pictures. Do a picture without laserdot, activate the laser and do a picture with laserdot. You simply just look for the pixels that changed to the color of your laser.
This will work in python, but it wont be as fast as doing it with C++. In Python i would use OpenCV. In C++ i would work with Video4Linux2, because its extremly fast doing stuff like this.
Get Better Results
If you want to get better results, you could use a "red filter" (if you use a red laser). Just buy a cheap one on any shop and glue it on your camera. This will make it much more easy to find the laser dot.
Comment if you have any questions.
I would like to know if there is a process to generate camera calibration patterns.
We can use paint or any other graphic tool and set the precise measurements but then we need to hard-code the point positions or create a txt/xml file.
Is there a software that exports the data to a file that we can upload in our software.
What about 3D targets like boxes and/or cubes. Is there a method to generate the correct data points?
Cheers.
For 2D targets such as checkerboards, I used to do it like user469049 describes. Which was quite time consuming. In the end I gave up and created a web tool that does all of the leg work:
https://calib.io/pages/camera-calibration-pattern-generator
I'm using inkscape:
http://dominoc925.blogspot.co.uk/2012/06/create-camera-calibration-chess-board.html
I usually create a pdf file used to print and save files as LaTeX with PSTricks extensions.
The tex file has paths, so for a square it has a \moveto command to set the starting point and it has \line to command to set the next points.
In the dominoc925 example they define black and white squares but I just define the black squares to avoid repeated points.
I have a simple file loader in my code to get the points, just search for the \moveto and \line commands and workout the points from there.
For the 3D targets I treat each patter as one view because I don't have the tools to build a precise 3D target.
So instead of having different views of one patter like in the Matlab toolbox, I treat each detected pattern as a view.
In other words, if you have a 3D object then the target on each face is treated as a independent view.
There is probably a more professional way to do the job but this is my process :)
I hope this helps.
It's known that 3D rendering is computation expensive.
And I want to use Apache Hadoop for distributed 3D rendering (rendering images or videos) to reduce rendering time. So after learning about Hadoop, I understand that I need 2 things:
Data, which will be visualized (probably it some kind of file, which contains instructions (like draw rectangle, set coordinates, set color etc.))
Some Tool/Program/Utility to render file described above. I want to invoke it from my program, pointing it to file with data. (it's good if this program has a command line API).
But I don't know anything about 3D rendering, so I need your help in suggesting tools (open-source) for render 3D images/videos. Also I don't know anything about input data. So it will be nice if you suggest me render tool + file format to render.
I heard about using Hadoop with .rib file format as data to visualize, and rndr program to render this data. So I need some analogue.
Please note, my goal is to more deeper learn about Hadoop and distributed computation, not about 3D rendering, so please suggest me simplest solution.
Thanks.
KISS: Gnuplot
If you really only care about using Hadoop, and your only requirement of the rendering is that it takes an input file and makes an image so you can show a completed animation, then I would suggest gnuplot. It is actually a graph-drawing program, but it takes scripts and produces image files, and most usefully for you you can enter mathematical formulae to draw rather than constructing 3d worlds to render.
You would simply prepare n files which are all the same except for an offset value for the time since start, and gnuplot would produce the appropriate frame.
This is the simplest option, and lets you concentrate on the Hadoop side. To show you how simple, this would produce a frame for an animation of a 3-blade fan spinning:
set xrange[-1:1]
set yrange[-1:1]
set polar
unset key
unset border
unset tics
set terminal png size 1000,1000
set output "frame_$FRAME.png"
plot cos(3*t+$FRAME/5)
A great thing about Gnuplot is that you type in commands in an interactive prompt to manipulate the graph, and these are the same commands you put in the script. So once you have something you're happy with, you can either do save 'newscript.gpt' or copy out the commands you used. You can recreate the graph by just running gnuplot newscript.gpt at a prompt.
Incidentally, it is easier to simulate hard-to-render scenes than to actually construct them, so just put a sleep command in the gnuplot script to make it take 15 seconds or however long.
The whole banana: Blender
Blender is a 3d rendering system. I believe it is used as a rendering system for some mainstream animations on server farms in exactly the manner you describe. It has quite a learning curve, but I think you should be able to pick up a tutorial or other pre-existing animation project files. From there you would need to work out how to invoke the rendering engine as a command for a specific frame. I've only ever done static rendering in blender, so I can't take you further there. This would be more impressive visually, but no more impressive academically, and you'll waste more time on that side of things.
My choice
Personally I would go with gnuplot. You can make 3d plots with the splot command rather than the 2d plot, and although it's not 3d scene rendering as you might be imagining, it achieves the purpose of making a picture using a script. You can begin with something totally basic like the above until you have your setup going, then introduce more complexity; from an implementation perspective, running a gnuplot script is easier than running a script that also requires a data file, but it's still easy to pre-generate the data and have gnuplot read that when you want to do command + script + data instead of command + script. The key is incrementally increasing the difficulty, not running before you can walk.
If you ultimately find you have spare time at the end and change it to using blender, then that's all free win, and you haven't jeopardised your hadoop project making it pretty.
Say i have this old manuscript ..What am trying to do is making the manuscript such that all the characters present in it can be perfectly recognized what are the things i should keep in mind ?
While approaching such a problem any methods for the same?
Please help thank you
Some graphics applications have macro recorders (e.g. Paint Shop Pro). They can record a sequence of operations applied to an image and store them as macro script. You can then run the macro in a batch process, in order to process all the images contained in a folder automatically. This might be a better option, than re-inventing the wheel.
I would start by playing around with the different functions manually, in order to see what they do to your image. There are an awful number of things you can try: Sharpening, smoothing and remove noise with a lot of different methods and options. You can work on the contrast in many different ways (stretch, gamma correction, expand, and so on).
In addition, if your image has a yellowish background, then working on the red or green channel alone would probably lead to better results, because then the blue channel has a bad contrast.
Do you mean that you want to make it easier for people to read the characters, or are you trying to improve image quality so that optical character recognition (OCR) software can read them?
I'd recommend that you select a specific goal for readability. For example, you might want readers to be able to read the text 20% faster if the image has been processed. If you're using OCR software to read the text, set a read rate you'd like to achieve. Having a concrete goal makes it easier to keep track of your progress.
The image processing book Digital Image Processing by Gonzalez and Woods (3rd edition) has a nice example showing how to convert an image like this to a black-on-white representation. Once you have black text on a white background, you can perform a few additional image processing steps to "clean up" the image and make it a little more readable.
Sample steps:
Convert the image to black and white (grayscale)
Apply a moving average threshold to the image. If the characters are usually about the same size in an image, then you shouldn't have much trouble selecting values for the two parameters of the moving average threshold algorithm.
Once the image has been converted to just black characters on a white background, try simple operations such as morphological "close" to fill in small gaps.
Present the original image and the cleaned image to adult readers, and time how long it takes for them to read each sample. This will give you some indication of the improvement in image quality.
A technique call Stroke Width Transform has been discussed on SO previously. It can be used to extract character strokes from even very complex backgrounds. The SWT would be harder to implement, but could work for quite a wide variety of images:
Stroke Width Transform (SWT) implementation (Java, C#...)
The texture in the paper could present a problem for many algorithms. However, there are technique for denoising images based on the Fast Fourier Transform (FFT), an algorithm that you can use to find 1D or 2D sinusoidal patterns in an image (e.g. grid patterns). About halfway down the following page you can see examples of FFT-based techniques for removing periodic noise:
http://www.fmwconcepts.com/misc_tests/FFT_tests/index.html
If you find a technique that works for the images you're testing, I'm sure a number of people would be interested to see the unprocessed and processed images.
I have a need to do some drawing using win32/GDI (Native, not .NET), and I've run into the following problem:
I need to draw lines that are "styled." For example, in the attached image, the line marked "A" is a straight line as far as my application data is concerned, it just needs to be drawn with the additional zigzag as a style. Of course, this is easy to do programatically, but it gets more complicated when the line can be at any angle ("B") or even a bezier curve ("C").
Now, I could do this all programatically, painstakingly doing the math to put a zigzag around each line possibility, but that will take a lot of time and, more importantly, be rather error prone.
Is it possible to just give windows/GDI a "style" to apply to the line, perhaps a bitmap like the one marked "D", and have it use that as a pen to draw the lines? If not, is there a more flexible and less error-prone way of doing this than writing a bunch of specific drawing code for each of the "styled" lines?
*Apparently first timers can't post images. Examples can be found at http://i.imgur.com/IC0T2.png
This is not possible in Win32 GDI. You will need to do the math yourself.
It should be noted however, that you can obtain the points used to make up the line or curve which should make it substantially easier.
See this "Hit-Testing" tutorial for an example.
http://msdn.microsoft.com/en-us/library/ms969920.aspx
For a bezier curve you would use Path Functions:
BeginPath
PolyBezier
EndPath
FlattenPath
For straight lines you could use:
LineDDA
As far as I know there's nothing in GDI or even GDI+ that would support this. The only line options you have are dash-patterns, compound-pens, dash caps, end caps, and fill brushes.
You might be able to trick one of those functions into drawing something vaguely akin to your wiggles for straight splines, but it definitely won't work for curved splines.
It shouldn't be too hard to do this however. Sure, it will take a day or so, but all you have to do is write a line and bezier interpolator, divide the curves into equal segments, find the tangents at all those segments and alternate left and right. You'll end up with an array of points which can be drawn very quickly as a polyline.
There's nothing that'll do this automatically. You'll have to write some code. You might want to look at the LineDDA API in GDI. It might simplify the math your code will need.
ExtCreatePen(), maybe? I don't know for a fact if it supports zigzagging...