• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
giugio

opencl and sobel

6 posts in this topic

hello.
I have this problem with sobel filter:
when the sobel filter finds an edge of a line, it finds the initial up edge and the end edge , then,a line in the sobel filter have two edge?.
Is possible to eliminate this behaviour and show only the start edge?
i'm trying to filter some letters in a texture but the words after the sobel filter are enlarged and confused.

for understand better the sobel filter:
The matrix system is a method for gain-time for find the edges?
isn't possible to test pixel for pixel the difference of color of neighbors pixels and see if it's in a range and if it is select the pixel?
it's only a compute method?
thanks.
0

Share this post


Link to post
Share on other sites
[quote name='giugio' timestamp='1354633499' post='5007092']
for understand better the sobel filter:
[/quote]
The double line is an effct of the sobel filter. The filter works on a pixel, therefor when sobel detects an edge at a pixel, it will detect it too on the other side too:


[CODE]
xxoo
xxoo
xxoo

[/CODE]
apply sobel on all x


[quote]
xXoo
xXoo
xXoo

[/quote]

apply soble on all o

[quote]
xXOo
xXOo
xXOo

[/quote]

There are several solutions:
1. Use the stencil buffer to detect the edge only on parts of the screen, e.g. the x surface only.
2. Use double resolution and scale it down afterwards (or use multisampling).
3. Use an other AA technique to make it less obviously. Edited by Ashaman73
1

Share this post


Link to post
Share on other sites
[quote name='Ashaman73' timestamp='1354690184' post='5007320']
The double line is an effct of the sobel filter. The filter works on a pixel, therefor when sobel detects an edge at a pixel, it will detect it too on the other side too:

There are several solutions:
1. Use the stencil buffer to detect the edge only on parts of the screen, e.g. the x surface only.
2. Use double resolution and scale it down afterwards (or use multisampling).
3. Use an other AA technique to make it less obviously.
[/quote]

very thanks Ashaman73,
I see your solutions but i'm a little newbe, can you explain me better a solution? the more simplest or post a link or a book and I study alone.
Thanks for your time

by.
0

Share this post


Link to post
Share on other sites
It depends on the requirements. What is your goal ? Have you examples of how it should look like ? Not every solution is suitable for all scenarios. E.g. rendering to an higher resolution and sampling it down (super sampling) will have a very good quality, but on the other hand makes the rendering of your scene ~4 times slower, which is often not feasible.

Edit:
A fast way to evaluate the AA option is to play around with the AA settings of your video card. Edited by Ashaman73
0

Share this post


Link to post
Share on other sites
my goal is to find edge on images(.jpg or tiff ecc..) taken from the scan of html tables with a border of a pixel.
I use opencl and 4 time slower is not a problem.
What is super sampler ?
0

Share this post


Link to post
Share on other sites
[quote name='giugio' timestamp='1354714545' post='5007387']
my goal is to find edge on images(.jpg or tiff ecc..)
[/quote]
uggh... well I thought, that you were talking about rendering outlines or something like this. In your case, image analysing, the solutions I sugguested will not work. If performance isn't an issue, have you played around with edge filters of image processing tools like photoshop or gimp ?
0

Share this post


Link to post
Share on other sites
[quote name='Ashaman73' timestamp='1354719159' post='5007409']
[quote name='giugio' timestamp='1354714545' post='5007387']
my goal is to find edge on images(.jpg or tiff ecc..)
[/quote]
uggh... well I thought, that you were talking about rendering outlines or something like this. In your case, image analysing, the solutions I sugguested will not work. If performance isn't an issue, have you played around with edge filters of image processing tools like photoshop or gimp ?
[/quote]

the performance are not an issue because i use opencl , but my goal is to create template tables and finding with the project after select a new table image, what is the most similar model from the analized(i use c++ and mysql for the models).
Then the performance are a little issue with opencl.
now for starting i would create o adapt a single edge sobel detector.
i found this on canny:
http://dasl.mem.drexel.edu/alumni/bGreen/www.pages.drexel.edu/_weg22/can_tut.html
the third image is a single edge canny.
thanks again
0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0