I am trying to build a collection of Visual similarity between images, being size, angle, color, rotation invariant for Content Based Image Retrieval.Quite agnostic about the platform but .NET, Java or Python are preferred. But if others are available, pls. suggest away.
I am quite familiar with OpenCV Match template and Match shapes. I have also looked at AForge.NET.
p.s. Something similar to http://www.imgseek.net/home would be ideal:
Content Based Image Retrieval is a field of heavy research. Unfortunately it is not my field of research, therefore I am unable to give you an authoritative suggestion on a viable algorithm. But I can give you the website where I would start looking for an answer:
CVPapers - Computer Vision Resource (check out the Computer Vision Paper Indexes)
Related
Here is my problem:
I must match two images. One image from the project folder and this folder have over 20.000 images. The other one is from a camera.
What I have done?
I can compare images with basic OpenCV example codes that I found in the documentation. OpenCV Doc I can also compare and find an image by using the hash of my image data set. It is so fast and it is only suitable for 2 exact images. One for query the other one is the target. But they are the same exact image.
So, I need something as reliable as feature matching and as fast as hash methods. But I can't use machine learning or anything on that level. It should be basic. Plus, I'm new to these stuff. So, my term project is on risk.
Example scenario:
If I ever take a picture of an image in my image data set from my computer's screen. This would change many features of the original image. In the case of defining what's in that image, a human won't struggle much but a comparison algorithm will struggle. Such a case leaves lot's of basic comparison algorithm out of the game. But, a machine-learning algorithm could solve the problem but it's forbidden to use in my project.
Needs:
It must be fast.
It must be accurate.
It must be easy to understand.
Any help is okay. A piece of code, maybe an article or a tutorial. Even an advice or a topic title might be really helpful to me.
Once saw this camera model identification challenge on kaggle. This notebook discusses about noise pattern changes with changing devices. May be you should look in to this and other notebooks in that challenge. Thanks!
I was wondering if anybody knew of an easy, robust way to generate depth images from 3d models (i.e. surface models, vertices with faces), with specifiable camera parameters.
I'd prefer "free" options if possible (e.g. pyOpengl or some open source Java library rather than say matlab).
I believe it is possible with the python blender api (noted here), but I'm hoping there's an easier way.
Note also that this question works only for that special case.
You can use DECA repository in Github. There, in ./demos, I used demo_reconstruct.py code to save the depth image.
I apologize if the answer was already somewhere, searching the interwebs did not return me the answer(s) I was looking for.
Situation : I have a small graph (a set of Edges and Nodes that is) - Now I want to display it in an interactive manner, and I would like to manipulate the display styles and symbols that are used for edges and nodes, programetically.
Hence kgraphviewer wont work - i want to do it programetically as stated.
I noticed VTK, comes with a lot of built is graph drawing algorithms. But seems to be a really large one.
Question : What are some alternatives to VTK ? Graphviz is probably one, but I can not confirm that graphviz comes with all the graph drawing algorithms as VTK - any other possibly smaller options, with all the built in graphs?
Side note : Some systems uses a static drawign widget, i.e. once the drawing is displayed, in an widget that the system comes with, you can not interact with the drawing using your mouse. The GNU implementation of IDL, GDL, has this problem. I would Like to avoid this.
Yes, I agree with you regarding the VTK's consideration: it's a powerful toolkit but it is (maybe) too much "big", and it's not so easy to configure a working VTK environment.
I don't have a great experience in the field of graphs, but a search leads to this other StackOverflow post. I think that Prefuse, listed under the Java section, could be of some interest. C++ itself seems to have a lot of choices, listed in various answers, here. I hope that it will help.
I used Gephi public domain graph visualization software on Linux. It was a quick way to get a 3 D. Picture which can be modified with line thickness to show an edge weight - good for comm network work.
As the title says, I'd like to program a 3d game (probably a BattleZone clone), but without the use of an API like OpenGL, DirectX, and the like. At the heart of the matter, I'd just like to learn how to draw basic 3d shapes to the screen and manipulate them. Don't care if it looks like crap. I've used OpenGL to achieve similar ends before, but really didn't learn about these topics.
The problem is, I have no idea where to start. I downloaded the Doom source code, but it's a bit over my head. Although I've programmed a bit, graphical matters are very much out of my depth.
I'd be very grateful if anyone could offer links or code (in any language) that would help me along in my purpose.
Sounds like an exciting project. I did something similar in the late 90's. Before OpenGL and DirectX became popular, there were a ton of great books on the subject.
Fundamentally you will have to learn how to
Represent 3D geometry
Transform that geometry (translate and rotate)
Project that geometry onto a 2D screen.
Each of those major topics has many sub-topics (for example, complex objects can be constructed from a number of polygons. You may want to limit polygons to being constructed of triangles only, or support other polygons. You may want to load common model formats e.g. .obj files so that you can create models with off the shelf tools).
The topics are way too broad for a detailed answer here. Whole books are written on the subject, including
Black Art of 3D Game Programming (Book, amazingly still available)
For a good introduction to the general topics, have a look at:
http://en.wikipedia.org/wiki/3D_projection
http://en.wikipedia.org/wiki/Orthographic_projection
http://en.wikipedia.org/wiki/Transformation_matrix#Perspective_projection
Doom, which you already looked at, used a special optimization called heightfield rendering and does not allow for rendering of arbitrary 3D shapes (e.g., you will not find a bridge in Doom that you can walk under).
I have the second edition of Computer Graphics: Principles and Practice in C and it uses SRGP (Simple Raster Graphics Programming) and SIGGRAPH which is a wrap-around SRGP, if you look up articles and papers on graphics research you'll see that both these libraries are used a lot, and they are way more direct and low level than the APIs you mentioned. I'm having a hard time locating them, so if you do, please give a link. Note that the third edition is in WPF, so I cannot guarantee much as to it's usefulness, and I don't know if the second edition is still in print, but I have found numerous references to the book, and it's got it's own page in Wikipedia.
Another solution would be the Win32 API which again does not provide much in terms of rendering, but it is trivial to draw dots and lines onto a window. I have written a few tutorials on it, but I didn't cover drawing pixels and lines, so they'll only be useful if you have trouble with the basics of setting up a window. Note that it is not intended for real-time rendering, so it may get slow.
Finally you can look at X11 programming, the foundation of most modern operating systems with a GUI. I haven't found the libraries for Windows, but again I didn't invest too much time on it. I know it is available for CIGWIN and for Linux in general though, and I believe it would be very interesting to look at the core of graphics since you're already looking under the hood of 3D graphics.
Im writing a game engine and I'm wondering what 3D model format should I use/load/export? Obj seems universal and easy but it also appears to be unreliable in that most models out there contain errors and it doesn't store anywhere near as much as other formats.
There appear to be formats specifically for games such as MD2/3/5 but Im not sure, I use wings3d if I model, and I don't know what other details beyond purely loading what I need and support from the format Id have to implement, such as would I need to implement IK? and can I use scripted per piece animation rather than Inverse kinematics and bone rigging?
Collada is an open XML based format for 3d models owned by the Khronos group(OpenGL standards body)
From the Collada.org FAQ:
The COLLADA 1.4.x feature set includes:
Mesh geometry
Transform hierarchy (rotation, translation, shear, scale, matrix)
Effects
Shaders (Cg, GLSL, GLES)
Materials
Textures
Lights
Cameras
Skinning
Animation
Physics (rigid bodies, constraints, rag dolls, collision, volumes)
Instantiation
Techniques
Multirepresentations
Assets
User data
Before worrying about what 3D formats you want to support, I think you should really focus on what features you are planning to implement in your engine. Write those down as requirements, and pick the format that supports the most features from the list... as you'll want to showcase your engine (I am assuming you are planning for your engine to be publicly available). You might even want to roll your own format, if your engine has specific features (which is always a good thing to have for a game engine).
After that, support as many of the popular formats as you can (.X, .3DS, .OBJ, .B3D)... the more accessible your engine is, the more people will want to work with it!
Collada is a nice and generic format, but like Nils mentions, it is not an ideal format for final deployment.
I use my own binary format. I've tried to use existing formats but always run into limitations. Some could be worked around, others where showstoppers.
Collada may be worth a look. I don't think that it's that good as a format to be read by a 3D engine. It's fine as a general data-exchange format though.
http://www.collada.org/mediawiki/index.php/Main_Page
+1 for Collada. You may also want a custom native binary format for really fast loading (usually just a binary dump of vertex/index buffer data, plus material and skeleton data, and collision data if appropriate).
One trend in the games industry is to support loading a format like collada in the developer build of the engine, but also have a toolchain that exports an optimized version for release. The developer version can update the mesh dynamically, so as artists save changes, the file is automatically reloaded allowing them an (almost) instant WYSIWYG view of their model, but still providing a fully optimised release format.
support Collada well, and then supply good converters to/from the other formats (this might be the hard part). This will give you maximum flexibility. Take a look at C4 engine
Collada is great, but it lives more on the 3D app side of things. ie it's best used for transferring 3D data between applications, not loading 3D data from within a games engine. Have you looked into Lua? It's widely used in games because its a scripting language that's both ridiculously quick (perfect for games) and very flexible (can be used to represent whatever data you need for your engine).