I’m a beginner and .  The problem is that inside of the bone tissue there are areas denser than others. To obtain the .stl file I have to decide which range of density value I want to include in my object. That fact results in an STL file with some holes bubble inside the volume.  To explain it better I could do an analogy: the volume that obtained is similar gruyere-cheese: outside the surface is smooth without any interruption inside there are a lot of bubbles/holes.  I can’t correct this problem during the transformation from CT to stl, so the question is: Do you know a method to fill the holes/bubbles? I don’t want to do it manually point by point because it will take hours.  I thought that I could make a hollow shell only of the external surface and fill it but I don’t know how to do it.  If you have other solution faster or smarter let me know.
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My mesh object is based on a CT bone scan so there are many inner geometries due to natural spaces in human bones. But I need a model that has no inner geometries. How do I fill inner holes and spaces with completely solid mesh?  Thanks  Update: I attached a screenshot of the "holes" in my mesh after boolean op.    booleaned:    original:
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I am trying to create contour lines and filled contours from a shapefile of height points using the contour plug in (have tried other tools but with no success).  The data is sourced from the UK Ordnance Survey in tiles of 400 x 400 points (NTF format). Each tile has been opened as a vector layer and then saved as a shp layer. The plug in will run properly with a single tile. However, the area I need is 3 x 3 tiles i.e. 1200 x 1200 points.   Initially I generated contour lines and filled contours for each of the 9 tiles. This is unsatisfactory since the spacing is slightly different for each tile according to its height range resulting in mismatch at tile boundaries. I then merged the 9 shp layers using the mmgis and vector menu merge. Running the contour plug in against either merged file fails with the dialogue box showing 'Not Responding'.  I am running QGIS 1.8 Lisboa on Windows 8 x64 pro with 32gb of memory and plenty of free disk space on all drives. I have had no problems with other imported layers, adding new layers of data. However, this is the first time I have attempted to generate a shaded layer or contour lines. I guess there must be a setting somewhere to allow the plug in to handle the larger data block - I found and increased the cache setting in 'options') or I am using the wrong tool for the job.  My project is mapping local history routes/settlements. The shading is needed to provide context.
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I was wondering how would i get a UV Sphere to act like the floating blob in the image?  As well as
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I have a large hole in a mesh that I'm trying to fill:    I've been trying an approach like this:    I'm finding it quite tough, since the number of vertices around the perimeter of the hole don't match a grid.  Is there a better approach to filling a hole like this?
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Let's consider two spheres in the $(x,y,z)$ 3D-space, both centered in the origin: the inner with radius $r$ and the outer with radius $r + dr$.   To compute the volume of the spherical shell between their two surfaces, one should simply proceed as follows:  $$dV = \frac{4}{3} \pi (r + dr)^3 - \frac{4}{3} \pi r^3 = \frac{4}{3} \pi (r^3 + 3 r^2 dr + 3 r dr^2 + dr^3 - r^3)$$  $$dV = \frac{4}{3} \pi (3 r^2 dr + 3 r dr^2 + dr^3)$$  but usually the last two terms between the brackets are neglected. I know $dr$ is infinitesimal, but can infinitesimals (raised to $n$-th power, $n&gt;1$) be neglected and still obtain an exact result? How can this be justified?
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In Skeptics.SE, a question regarding the skulls of children arose. Depicting a scary skull where the permenent teeth are "hidden" inside the jaws and the milk teeth are in the their place.  After all milk teeth fall out, and the permanent teeth "rise", do the holes left by them filled up, or do we go around with holes in our jaws?    The picture:
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A hole of radius r is bored through the center of a sphere of radius $R &gt; r$. Find the volume of the remaining portion of the sphere.    I'm not sure on how to approach this problem. What is the most difficult part is knowing how to set up the bounds of integration. Mainly, how does one set up the bounds either when regarding cylindrical shells or washers? How do we exactly arrive at this (is it the points in which we do the sum of the tiny elements of area $dA$)? Is there a "fool-proof" way of knowing the bounds?  I was trying to solve this problem using the washer method in terms of y, but I'm not sure on how to set up my bounds of integration.  Thank you very much for your help in advance.
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I'm relatively new. I know how to make a water bottle starting with a circle and extruding upwards while using a combo of extrude and scaling to make indents, but how would I do something like this? I'm still trying to wrap my head around some of the photos I see out there. This is such an incredible program. Thanks for your help!
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I'm looking for a shapefile containing an 1000m or 2000m UTM grid ("graticule"). All I was about to find on the web is a 10000m UTM grid (here: ) and I am aware that a 1000m UTM grid for the whole world might be quite big.  That's why I'm now wondering if and how it would be possible to generate such a shapefile for a part of the world. I would prefer to use open source tools like gdal. Others output formats than a shapefile might be ok too.   Has anyone an idea?
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Assume that we have voxelized a 3D scene into a regular 3D grid of cubes, storing the average (diffuse) radiance and some flag indicating whether or not a voxel is empty. Next, the finer levels of the 3D texture (voxels) are downsampled to get coarser levels ("pre-integrated") which will be stored as MIP levels for that texture. (I know that some sparser structures can be used instead, but a regular grid is conceptually the most easiest to master first.)  Now, given that we have our surface position (and thus also the voxel we are in), how does voxel cone tracing work and how is it applied?
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I have a certain geometry. See image. I need to create 3 creases/cavities on the surface. I tried 2 methods, see images. One is Knife Projecting mesh edges onto the surface, and then fiddling around with it. The other is using Difference Boolean operation (including cleaning up triangles afterwards). Both methods give terrible results, plenty of artefacts. What is a clean way to achieve the result? Or do I have to unwrap the mesh and create a bump map with these creases?
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A reverse clip saves only the part of your spatial object that is outside the bounds of another object, as opposed to a regular clip which saves the parts that are inside the other object.    shows how to do it in ArcMap.  How do I do this in R?  Reproducible example (on Linux machines):  system("wget 'https://github.com/Robinlovelace/Creating-maps-in-R/archive/master.zip' -P /tmp/") unzip("/tmp/master.zip", exdir = "/tmp/master") uk &lt;- readOGR("/tmp/master/Creating-maps-in-R-master/data/", "ukbord") lnd &lt;- readOGR("/tmp/master/Creating-maps-in-R-master/data/", "LondonBoroughs") plot(uk) plot(lnd, add = T, col = "black")   What I want here to do is to save all of the UK except for London. Visually, I want the black shape in the resulting image to be a hole.
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I have a 3d landscape created from a heightmap. I'd like to "carve" some holes in that terrain. That will allow me to create bridges, caverns and tunnels inside it.    That operation will be done in the game editor so it doesn't need to be realtime. In the end, rendering is done using traditional polygons.  What would be the best/easiest way to do that ? I already think about several solutions :  Solution 1  1) Create voxels from the heightmap (very easy). In other words, fill a 3D array like this : voxels[32][32][32] from the heightmap values.  2) Carve holes in the voxels as i want (easy too).  3) Convert voxels to polygons using some iso-surface extraction technique (like marching cubes).  4) Reduce (decimate) polygons created in 3).  This technique seems to be the most promising for giving good results (untested). However the problem with marching cubes is that they tends to produce lots of polygons thus reducing them is mandatory. Implementing 4) also seems not trivial, i have read several papers on the web and it seems pretty complex. I was also unable to find an example, code snippet or something to start writing an algorithm for triangle mesh decimation. Maybe there is a special decimation algorithm (simpler) for meshes created from marching cubes ?  Solution 2  1) Create some triangle mesh from the heighmap (easy).  2) Apply severals 3D boolean operation (eg: subtraction with a sphere) to carve the mesh.  3) apply some procedure to reduce polygons (optional).  Operation 2) seems to be very complex and to be honest i have no idea how to do that. Also applying many boolean operation seems to be slow and will maybe degrade the triangle mesh  every time a boolean operation is applied.
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Consider the curve $\frac{1}{x}$  where $x \geq 1$. Rotate this curve around the x-axis.   One Dimension - Clearly this structure is infinitely long.  Two Dimensions - Surface Area = $2\pi\int_∞^1\frac{1}{x}dx = 2\pi(\ln ∞ - \ln 1) = ∞$   Three Dimensions -  Volume = $\pi\int_∞^1{x}^{-2}dx = \pi(-\frac{1}{∞} + \frac{1}{1}) = \pi$   So this structure has infinite length and infinite surface area. However it has finite volume, which just does not make sense.  Even more interesting, the "walls" of this structure are infinitely thin. Since the volume is finite, we could fill this structure with a finite amount of paint. To fill the structure the paint would need to cover the complete surface area of the inside of this structure. Since the "walls" are infinitely thin, why would a finite amount of paint not be able to cover the outside of the "walls" too?  Please help me make sense of this whole thing.
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I have tried everything to fill an invisible container with particles but the particles just seems to sinks to the bottom and they don't fill the container. I am trying to create something like in the video below how balls take the shape and fill up the space i want to create something like this. Please help.  Edit : have also tried the molecular script but that doesn't seem to work as well.
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I have an object already created in blender, a tree, or a human, or a pipe.. and I need this to be drilled with multiple holes.   The holes are painted in an image, that is, it is an image that has a repeating an images pattern (they can be circles, squares, or any form).  Here are some examples for drilling-pattern:
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A question occurred to me when browsing SE this evening, just curious.  What specifies the inside of a 3D construct? If I have a hollow sphere, what's to say that the world isn't the inside, and the center of the sphere isn't the outside. Picture the Asylum in the Hitchhiker's Guide to the Galaxy series, if you have read that.  Additionally, if the inside of a 3D object is defined as what is smaller than the outside, what happens when there is a a sphere with a volume equivalent to 51% of the universe?