I'm not sure if SO is the best site for this question, but I saw some other sketch-up tags...
I've found a bunch of tutorials that show how to draw a sphere. Here's one for example. However, whenever I try it I get a half sphere with a hole in the top:
What am I doing wrong?
To Clarify: The half sphere needs to have a radius of 7/32". I noticed that when I use this measurement (and other smaller ones) I get the problem. I tried it without specifying 7/32" and drew a somewhat bigger second circle and it worked:
How can I get a solid half sphere that has a radius of 7/32"?
I'll leave this for others' reference. I ended up drawing at 4X and then used the scale tool to shrink it down to 25% after the fact. Maybe SU doesn't do so well with smaller sizes.
Related
So, I'm attempting to create a simple dynamic endless terrain using simplex noise.
So far I've got the noise working just fine - however I am having issues with the terrain having discontinuities at the edges. At first I thought this was due to the fact that I was not calling SetNeighbors on the Terrain objects, but adding this did not seem to yield any improvement.
terrain.GetComponent<Terrain>().SetNeighbors(left, top, right, bottom);
This problem seems to be caused by the slight differences in height between each terrain position - but making these set the same will effect the terrain quality (will reduce how jagged the terrain can be in certain cases) and generally seems inelegant. I've been going through the unity docs trying to find how to address this, but have yet to find anything.
Is there something I'm missing? Or is my only option to fiddle the heights on one of the sides to match the other?
Thanks for reading, appreciated as always.
Terrain image for reference
A couple things-
First, make sure you're setting SetNeighbors() on ALL the terrain objects, not just one.
Secondly, if the terrain don't match up exactly, it either means that the terrains aren't calculating their data quite correctly, or there's some floating point error going on. However, I have a suspicion that it's the first one, given that manually changing the points affects the quality. Make sure you know that terrains have n^2 + 1 points, and also make sure that the point to query from your simplex function with is calculated in world space.
If you can't figure it out, post your code and I'll take a look.
Also, your terrain might look better if you used octaved (a.k.a factal) noise on your Simplex noise function, depending on what you're looking for.
Cheers!
I have an image which looks like this:
I have a task in which I should circle all the bottles around their opening. I created a simple algorithm and started working it. My algorithm follows:
Threshold the original image
Do some morphological opening in it
Fill the empty holes
Separate the portion of the image using region props such that only the area equivalent to the mouth of the bottles is selected.
Find the centroid for each and draw circle around each bottle.
I did according to the algorithm above and but I have some portion of the image around which I draw a circle. This is because I have selected the area since the area of the mouth of bottle and the remained noise is almost same. And so I yielded a figure like this.
The processing applied on the image look like this:
And my final image after plotting the circle over the original image is like this:
I think I can deal with the extra circle, that is, because of some white portion of the image remained as shown in the figure 2 below. This can be filtered out using regionproping for eccentricity. Is that a good idea or there are some other approaches to this? How would I deal with other bottles behind the glass and select them?
Nice example images you provide for your question!
One thing you can use to detect the remaining bottles (if there are any) is the well defined structure of the placement of the bottles.
The 4 by 5 grid of the bottle should be relatively easy to locate, and when the grid is located you can test if a bottle is detected at each expected bottle location.
With respect to the extra detected bottle, you can use shape features like
eccentricity,
the first Hu moment
a ratio between the perimeter length squared over the area (which is minimized for a circle) details here
If you are able to detect the grid, it should be easy to located it as an outlier (far from an expected bottle location) and discard accordingly.
Good luck with your project!
I've used the same approach as midtiby's third suggestion using the ratio between area and perimeter called shape factor:
4π * Area /perimeter^2
to detect circles from a contour traced image (from the thresholded image) to great success;
http://www.empix.com/NE%20HELP/functions/glossary/morphometric_param.htm
Regarding the 4 unfound bottles, this is rather tricky without some a priori knowledge of what it is you're looking at (as discussed using the 4 x 5 grid, then looking from the centre of each cell). I did think that from the list of contours, most would be of the bottle tops (which you can test using the shape factor stuff), however, one would be of a large rectangle. If you could find the extremities of the rectangle (from the largest contour in terms of area), then remove it from the third image, you'd be left with partial circles. If you then contour traced those partial circles and used a mixture of shape factor/curve detection etc. may help? And yes, good luck again!
Maybe I'm asking this too soon in my research, but I'd better know if this is possible sooner than later.
Imagine I have the following square printed on a paper on top of a table:
The table is brown, so it does not match with any of the colors in the square. Is there a way for me, from a common iPhone camera (non-stereo view), to figure out the distance and angle from which Im looking at the square in the table?
In the end what I'm looking for is being able to draw a 3D square on top of this one using the camera image, but I'm not sure if I am going to be able to figure out the distance and position of the object in space using only a 2D image. Any hints are well appreciated.
Short answer: http://weblog.bocoup.com/javascript-augmented-reality
Big answer:
First posterize, Then vectorize, With the vectors in your power you may need to do some math tricks to define, based on the vectors position, the perspective and then the camera position.
Maybe this help:
www.pixastic.com/lib/docs/actions/posterize/
github.com/selead/cl-vectorizer
vectormagic.com/home
autotrace.sourceforge.net
www.scipy.org/PyLab
raphaeljs.com/
technabob.com/blog/2007/12/29/video-games-get-vectorized/
superuser.com/questions/88415/is-there-an-open-source-alternative-to-vector-magic
Oughta be possible. Scan the image for the red/blue/yellow pattern, then do edge detection to figure out how warped the squares are (they'll be parallelograms in anything but straight-on view). Distance would depend on the camera's zoom setting and scan resolution. But basically you'd count how many pixels are visible in each of the squares, run that past the camera's specs and you should be able to determine a rough distance.
I am fairly new to programming and I'm doing it, at this point, just to educate myself and have fun.
I'm having a lot of trouble understanding some OpenGL stuff despite having read this great article here. I've also downloaded and played around with an example from the apple developer site that uses a .png image for a sprite. I do eventually want to use an image.
All I want to do is take an image and warp it such that it's four corners end up at four different x,y coordinates that I supply. This would be on a timer of sorts (CADisplayLink?) with one or more of these points changing at each moment. I just want to stretch it between these dynamic points.
I'm just having trouble understanding exactly how this works. As I've understood some example code over at the developer center, I can use:
glVertexPointer(2, GL_FLOAT, 0, spriteVertices);
where spriteVertices is something like:
const GLfloat spriteVertices[] = {
-0.90f, -.85f,
0.95f, -0.83f,
-0.85f, 0.85f,
0.80f, 0.80f,
};
The problem is that I don't understand what the numbers actually mean, why some have negatives infront of them, and where they are counting from to get the four corners. How would I need to change normal x,y coordinates that I get in order to plug them into this? (the numbers I would have for x,y wouldn't look like numbers between 1 and 0 would they? I would like something akin to per pixel accuracy.
Any help is greatly appreciated even if it's just a link to more reading. I'm having trouble finding resources for a newb.
It isn't as complicated as it seems at first. Each pair of numbers relates to an x,y position on the screen. So, 0.80f, 0.80f, would say go to 80% of the drawable area for both x and y(left to right, down to up). While -0.80,-0.80 would say go to 80% of the drawable area from right to left, up to down. The negatives just switch the sides. A point of note, openGL draws down to up(as if you were looking up a building from the ground), while the iPhone draws up to down (as though you were reading a book).
To get pixels, you multiply the float value by drawable area 1024 X 0.8 = 819.2.
This tutorial is for textures, but it is amazing and really helps you learn the coordinate systems:
http://iphonedevelopment.blogspot.com/2009/05/opengl-es-from-ground-up-part-6_25.html
I have some data points which I have devided into them into some clusters with some clustering algorithms as the picture below:(it might takes some time for the image to appear)
alt text http://www.freeimagehosting.net/uploads/05a807bc42.png
Each color represents different cluster. I have to draw polygons around each cluster. I use convhull for this reason. But as you can see the polygon for the red cluster is very big and covers a lot of areas, which is not the one I am looking for. I need to draw lines(ploygons) exactly around my data sets. For example in the picture above I want a polygon that is drawn exactly the same(and around) as the red cluster with the 3 branches. In other words, in this case I need a polygon with 3 branches to cover my red clusters not that big polygon that covers the whole area. Can anyone help me with this?
Please Note that the solution should be general, because the clusters will change in each run of the algorithm, so it needs to be in a way that is general.
I am not sure this is a fully specified question. I see this variants on this question come up quite often.
Why this can not really be answered here: Imagine six points, three in an equilateral triangle with another three in an equilateral triangle inside it in the same orientation.
What is the correct hull around this? Is it just the convex hull? Is it the inner triangle with three line spurs coming out from it? Does it matter what the relative sizes of the triangles are? Should you have to specify that parameter then?
If your clusters are very compact, you could try the following:
Create a grid, say with a spacing of 0.1.
Set every pixel in the grid to 1 if there's at least one data point covering it, set the pixel to 0 if there is no data point covering the pixel.
You may need to run imclose on your mask in order to fill little holes inside that have not been colored due to sheer bad luck.
Extract the border pixels using, e.g. bwperim. This is the outline of the polygon you're looking for.