I am  trying to delete an object in my video using blender.  I think masking might have something to do with it.  Or I could be wrong.  For example:  I might have a stool with someone sitting on it.  Then in blender I want to get rid of the stool so it looks as if the actor is floating.  Help is appreciated.  Thanks  Note I am talking about live action video being edited in blender
I'm trying to use a mask to hide a part of a render layer, so that when the render layer is shown over a movie, some parts in the movie will appear to be in front of the render layer.  For example, assume I want to add a box to this image, so that it would look like it's behind the person:    I created the following simple object:    If I render the object, it looks great - the object is solid, everything else is transparent (I didn't use any 'sky'):     Now I create a mask to describe the standing person (or at least the part that would otherwise be covered by the box):    What I want now is to create a "hole" in the rendered box, so that when I use Alpha-over, the box look as if it's behind the person, but I can't find an easy way to do that. My first guess was to use 'Set alpha' to apply the mask (inverted) as an alpha for the rendered layer, but this doesn't look good:    The mask did create a "hole" where it should, but now all the other pixels are not transparent. How can I "retain" the transparent pixels while setting more pixels to be transparent based on the mask (use it as a matte)?  Note: I can do this with (I'm ashamed to say) some math work on the alpha channel, but it just doesn't seem right:    Thanks, and sorry for the [oh so] long question.
Let's say you have the ability to shine some light into a perfectly round sphere and the sphere's interior surface was perfectly smooth and reflective and there was no way for the light to escape.  If you could observe the inside of the sphere, what would you observe? A glow? And would temperature affect the outcome?  Seems silly, it's just something I've always thought about but never spent enough time (until now) to actually find an answer. Replacing whiteness with transparency in Photoshop I want to replace the whiteness in pixels with transparency in the same way as described in  - i.e. for lighter pixels to be made proportionally as transparent. All solutions found via google are based on magic wand or other methods that do not work for my needs.  I'm sure there used to be a way to do this in earlier version of Photoshop (a simple functions to replace a colour with transparency), but I can't seem to do it in CS6.  Replace Colour has no alpha options.. Checking from shell script if a directory contains files From a shell script, how do I check if a directory contains files?  Something similar to this  if [ -e /some/dir/* ]; then echo "huzzah"; fi;   but which works if the directory contains one or several files (the above one only works with exactly 0 or 1 files). Make Blender usable on high resolution screen I've just installed QGIS 3.2.2 and after installation, tried to use the Plug in Manager to install the OpenLayers plugin.  But it's not in the list to install.    Any ideas? What may happen after a stack of spells resolves? Within the same phase, once a stack of spells has resolved in its entirety, is priority once again given to a player so that more spells may be cast?  For example:  I attack with a creature. Opponent opts not to block. Now, I want to buff (e.g. +3/+3) my creature multiple times, but I'm afraid of my opponent responding with a burn (e.g. Deal 3 damage) spell at the top of the stack. Can I buff once, ask if opponent wants to respond, then allow the stack to resolve. Then, in the same phase, cast more buff? Is my proof of convergence for $\sum\limits^{\infty}_{n=1} \frac {2^n} {n^n}$ true? I want to prove that $\sum\limits^{\infty}_{n=1} \frac {2^n} {n^n}$ is convergent.  Therefore I want to use that it will be convergent if $\lim\limits_{n \to \infty}|\frac {2^{n+1}} {n^n}| &lt; 1$ is true.  But I am not sure if all of my steps are legal to do in order to do it. Here is what I came up with:  $$\lim_{n \to \infty}|\frac {2^{n+1}} {n^n}| &lt; 1$$ $$\lim_{n \to \infty}|\frac {\sqrt[n]{2^{n}} \sqrt[n]{2}} {\sqrt[n]{n^n}}| &lt; \sqrt[n]1$$ $$\lim_{n \to \infty} \frac {2 \sqrt[n]2} {n} &lt; 1$$ $$0&lt;1$$  $\Rightarrow$ It is true. How to correct for small p-value due to very large sample size I am running into a problem where an independent variable, which should have no predictive power on the dependent variable based on domain knowledge, comes out with very small p-value because the sample size is very large(~100,000). If I only use &lt; 5000 data points, then the p-value becomes large enough to support the prior that the variable is insignificant. However, I don't think tweaking the sample size to get to the desired conclusion is a good practice. Is there any procedure to adjust for small p-value simply due to huge sample size? Problem: Prove that $1^2+2^2+\cdots+n^2=\frac{n(n+1)(2n+1)}{6}$ for $n \in \mathbb{N}$.  My work: So I think I have to do a proof by induction and I just wanted some help editing my proof.  My attempt:  Let $P(n)=1^2+2^2+\cdots+n^2=\frac{n(n+1)(2n+1)}{6}$ for $n \in \mathbb{N}$.  Then $$P(1)=1^2=\frac{1(1+1)(2+1)}{6}$$ $$1=\frac{6}{6}.$$ So $P(1)$ is true.  Next suppose that $P(k)=1^2+2^2+\cdots+k^2=\frac{k(k+1)(2k+1)}{6}$ for $k \in \mathbb{N}$. Then adding $(k+1)^2$ to both sides of $P(k)$ we obtain the following: $$1^2+2^2+\cdots+k^2+(k+1)^2=\frac{k(k+1)(2k+1)}{6}+(k+1)^2$$ $$=\frac{2k^3+3k^2+k+6(k^2+2k+1)}{6}$$ $$=\frac{2k^3+9k^2+13k+6}{6}$$ $$=\frac{(k^2+3k+2)(2k+3)}{6}$$ $$=\frac{(k+1)(k+2)(2k+3)}{6}$$ $$=\frac{(k+1)((k+1)+1)(2(k+1)+1)}{6}$$ $$=P(k+1).$$ Thus $P(k)$ is true for $k \in \mathbb{N}$. Hence by mathematical induction, $1^2+2^2+\cdots+n^2=\frac{n(n+1)(2n+1)}{6}$ is true for $n \in \mathbb{N}$. Probability of first actor winning a "first to roll seven with two dice" contest? Two players P and Q take turns, in which they each roll two fair and independent dice. P rolls the dice first.  The first player who gets a sum of seven wins the game. What is the probability that player P wins the game? No grub menu after Ubuntu install, booting directly into Ubuntu Why did Dumbledore drink the potion in the attempt to get a Horcrux? When Albus Dumbledore  finally reaches the island with Harry Potter and finds out that you can't get near the potion, he made a cup and drank it. Why couldn't he just have poured the potion on the "floor"? Why couldn't he have made a big cup to hold almost everything inside the basin? $AB-BA=I$ having no solutions The following question is from Artin's Algebra.      If $A$ and $B$ are two square matrices with real entries, show that $AB-BA=I$ has no solutions.    I have no idea on how to tackle this question. I tried block multiplication, but it didn't appear to work. I know blender can display both orthographic and perspective projection. But, when we look at a cube in blender's viewport, I'm unable to distinguish by eye, if the projection in the viewport is a one-point, a two-point or a three-point perspective. What does blender use, and is this something changeable? What is the term for accusing a person of mischief through invented, twisting and changeable terminology? What is the term for accusing a person of invented wrongdoing in such a way that he cannot respond or even clearly understand the accusations? For example, frequently reversing the definitions of the terminology used, or basing argumentation on hints and roundabout phrasings, metaphors, invented-on-the-fly floating definitions and rules to fit with the accusations.    Update: I think inquisitorial is the most proper term for context in which the result does not depend on the argumentation of one of the sides.    Though, jargonaut was completely unheard by me and incrementally more useful. Joining lots of small polygons to form larger polygon using PostGIS? How do I create an immutable Class? Using Static Variables in a Custom Module I'm trying to define a static variable for use in my custom module. I want it to let me pass a number from function to function. I'm using drupal_static() but I can't get it to work. How do I do this?  This is the code I'm using to define my static variable.  $var = &amp;drupal_static(__FUNCTION__); if (!isset($var)) {   // generate contents of static variable   $var = '8'; } return $var;   I've tried putting it in a custom module.    function viewusercontact_locateuser($value, $key, &amp;$counter) {    global $user;     /**********In here***********/     if ($value['uid'] == $user-&gt;uid) {       ........    } }   I can't seem to get it to work. What am I doing wrong?  (I got my code from the following guides) How can I accept the Microsoft EULA agreement for ttf-mscorefonts-installer? What is the best way to explain how to choose between "its" and "it's"? Probably one of the most frequent grammar mistakes in the English language is:     The dog sat on it's mat.   Since spelling checkers don't catch it, and it is even logical, since you would correctly write:     The dog sat on Fluffy's mat.   What is the best way to explain to a learner of English how to choose between it's and its?