I have a binary volume that I have read into itk::Image. After creating the surface and the mesh, there are some wholes that need to be closed. I need to create a closed surface, however, the object values are reaching to the first row (horizontal or axial view of the volume) and also there are wholes in the starting and ending slice (z-direction), that is not letting the surface to be closed. There are some wholes on the surface as well. What solution do you suggest?
To fix the holes at the edges of the volume, simply pad out the volume with blank space so that the object does not reach the edge of the volume.
For other holes you could try VTK's FillHolesFilter:
https://vtk.org/doc/nightly/html/classvtkFillHolesFilter.html
You might have to play with the HoleSize parameter to get good results.
Related
I made a mesh from a Digital Elevation Map that spanned 1x1 degree box of geography, but when I scale the mesh up to 11139m in blender I get these visible jagged shadows on the peaks of the mesh. I'd prefer to not scale everything down but I suppose I can, it just seems like a strange issue I want to better understand.
My goal is to use the landscape in a WebVR application, but when I put this mesh into an Aframe scene it also has this issue. Thanks for any tips!
Quick answer:
I think this may be caused by the clipping start/end values. Also called near/far clipping planes. Adjusting them may fix the issue but also limit the rendering distance.
Longer explanation:
Take a look at this:
It's a simple grayscale, but imagine it is scaled across your entire scene depth (Z depth buffer). The range of this buffer is set by the start/stop clipping (near/far) camera setting.
By default Blender has its start/stop (near/far) clipping set to 0.01 - 1000.
While A-Frame has it like 0.005 - 10000. You may find more information here: A-Frame camera #properties
That means the renderer has to somehow fit every single point in that range somewhere on the grayscale. That may cause overlapping or Z-fighting because it is simply lacking precision to distinguish the details. And that is mainly visible at edges/peaks because the polygons are connected there at acute angles and the program has to round up the Z-values. That causes overlapping visible as darker shadows (most likely the backside of the polygon behind).
You may also want to read more about Z-fighting because it is somewhat related.
Example
I am attempting to come up with a quick and efficient means of translating a 3d mesh into a projected AABB. In the end, I would like to accomplish something similar to figure 1 wherein only the area of the screen covered by the cube is located inside the bounding box highlighted in red. ((if it is at all possible, getting the area as small as possible, highlighted in blue, would increase efficiency down the road.))
Figure 1. https://i.imgur.com/pd0E20C.png
Currently, I have tried:
Calculating the point position on the screen using camera.unproject_position(). this failed largely due to my inability to wrap my head around the pixel positions trending towards infinity. I understand it has something to do with Tan, but frankly, it is too late for my brain to function anymore.
Getting the area of collision between the view frustum and the AABB of the mesh instance. This method seems convoluted, and to get it in a usable format I would need to project the result into 2d coordinates again.
Using the MeshInstance VisualInstance to create a texture wherein a pixel is white if it contains the mesh instance, and black otherwise. Visual instances in general just baffle me, and I did not think it would be efficient to have another viewport just to output this texture.
What I am looking for:
An output that can be passed to a shader informing where to complete certain calculations. Right now this is set up to use a bounding box, but it could easily be rewritten to also use a texture. It also could be rewritten to use polygons, but I am trying to keep calculations to a minimum in the shader.
Certain solutions I have tried before have worked, slightly, but this must be robust. The camera interfacing with the 3d object will be able to move completely around and through it, meaning at times the view will be completely surrounded by the 3d model with points both in front, and behind.
Thank you for any help you can provide.
I will try my best to update this post with information if needed.
This question is very similar to that posed here.
My problem is that I have a map, something like this:
This map is made using 2D Perlin noise, and then running through the created heightmap assigning types and color values to each element in the terrain based on the height or the slope of the corresponding element, so pretty standard. The map array is two dimensional and the exact dimensions of the screen size (pixel-per-pixel), so at 1200 by 800 generation takes about 2 seconds on my rig.
Now zooming in on the highlighted rectangle:
Obviously with increased size comes lost detail. And herein lies the problem. I want to create additional detail on the fly, and then write it to disk as the player moves around (the player would simply be a dot restricted to movement along the grid). I see two approaches for doing this, and the first one that came to mind I quickly implemented:
This is a zoomed-in view of a new biased local terrain created from a sampled element of the old terrain, which is highlighted by the yellow grid space (to the left of center) in the previous image. However this system would require a great deal of modification, as, for example, if you move one unit left and up of the yellow grid space, onto the beach tile, the terrain changes completely:
So for that to work properly you'd need to do an excessive amount of, I guess the word would be interpolation, to create a smooth transition as the player moved the 40 or so grid-spaces in the local world required to reach the next tile over in the over world. That seems complicated and very inelegant.
The second approach would be to break up the grid of the original map into smaller bits, maybe dividing each square by 4? I haven't implemented this and I'm not sure how I would in a way that would actually increase detail, but I think that would probably end up being the best solution.
Any ideas on how I could approach this? Keep in mind it has to be local and on-the-fly. Just increasing the resolution of the map is something I want to avoid at all costs.
Rewrite your Perlin noise to be a function of position. Then you can increase the octaves (and thus the detail level) and resample the area at a higher resolution.
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I've made a game map in blender and accidentally applied the objects transformations.
I don't really understand how it works. My guess is that the properties getting zeroed because the origin of the object is being set to its center.
I've tried the "clear origin" option, but it doesn't work. Any suggestions?
Thank you,
Amir.
Presuming that I understood you correctly:
Alt+R : Clear Rotation
Alt+G : Clear Location
Alt+S : Clear Scale
When you have a complex object with a container and child transforms that hold the actual meshes, if you mistakenly Apply Location CTRL+A on your container (and it wasn't in the center) it will indeed annoyingly show the location gizmo for the object at the center of the scene (possibly with dotted lines pointing to the child origins).
To fix this (even if you applied location to the child transforms as well), Select your meshes (for example with B) and Set Origin CTRL+SHIFT+ALT+C to Geometry. (This will fix locations of transforms with meshes.)
Next either go to Edit mode TAB and select two (or more) of the extreme vertices - basically corners of the bounding box and Snap SHIFT+S Cursor to Selected (that should get your cursor to the very center of your collection).
Next Unparent ALT+P your transforms (Clear and Keep Transformation), Select your original parent container and Snap SHIFT+S Selection to Cursor.
Finally Select the children again and Parent CTRL+P them back to the container (by Selecting it last).
In the case of Scale and Rotation, if the Undo CTRL+Z didn't help you, then you'll need to manually adjust them back to how they used to be. Point of reference usually helps, if you've got a backup of a previous version, you can just compare to that. Otherwise you can create basic Cube Mesh SHIFT+A or use the grid and Ruler/Protractor (Tool Shelf T > Grease Pencil > Ruler/Protractor) to help you (notice the helpful CTRL guidance).
For Scale S, measure against known length (measured changed length / measured original length), divide the Scale (Properties > Object > Scale) by the resulting quotient and apply the result as new Scale. (Notice, that if you didn't change the Scale uniformly, you might need to do this separately for each axis.)
For Rotation R you'll need to do similar measurements and calculations, though simple manual adjustment with the help of CTRL might get you desired results.
After you've corrected Scale and Rotation, remember to Apply CTRL+A your result (but preferably not the Position).
Once you apply transformation to the object data, there is no way to get it back automatically since its a destructive operation (like flattening layers of an image or scaling it down).
Besides manually setting to the cursor and making that the origin, but that still misses rotation and scale.
you can use Origin tool with 'Origin To Geometry' option to reset the pivot, but thats all.
OK.
I'm in essense trying to make my own interpretation of the NES hardware, so I can make a game that ideally would resemble what a NES game would look like. I'm currently stuck with how to adjust how to draw the playfield to the video memory (back buffer).
BACKBUFFER
The NES had restrictions on the nametable, or backbuffer. For my example, the backbuffer is 256x240pixels big, or the size of one screen. If I drew this to the TV, it would fill up the screen perfectly. Now, if I drew this to the screen with an offset of X=5, the entire image would be shifted and would wrap around the screen.
For example.....
ORIGINAL, NO OFFSET: DRAWN WITH OFFSET OF X=5:
ABCDEFGHIJK GHIJKABCDEF
DRAWN WITH OFFSET OF X=-5:
FGHIJKABCDE
The screen is split up into squares 8x8 pixels each, totalling 32x30 rows and columns. (256x240 pixels). The offset is represented in pixels - not columns; so in theory, I could offset the screen by 5 pixels and every column would be shifted to the right by five pixels.
LEVEL DESIGN
My stages are made up of screens, containing data that is represented in 16x15 rows and columns, each by 16x16 pixels. This is to emulate how many NES games stored level data - each tile holds info about what should be in each 8x8 block.
E.g.:
AA
BC with A,B,C,D representing what 8x8 graphic should go where
Level design is represented by this as well, with each number being a different screen and - meaning nothing, null.
-----
-123-
---4-
--54-
-----
CHARACTER PLACEMENT
This is easy. I already know how I can determine which table, row, and column my characters are on based on their absolute positioning. I can also determine the relative positioning within the screen.
With this info, I can easily figure out which columns are to the left and right of the character, if any (if the character is at the left side of screen 1, thered be no more level left)
SO HERE'S THE QUESTION DUN DUN DUN
How do I draw my levels to the screen, so that they scroll from one to the next.
It would be relatively easy to draw one full screen at a time, and when the character gets to the edge just flip to another screen.
However, the problem I'm conceptually having is that I need to 'stream' the level data onto the screen. That, lets say the character moves 24 pixels to the right. The BG needs to move as well.
So, I need to adjust the scrolling of the backbuffer by 24 pixels. However, just scrolling alone will cause the screen to wrap over, diplsaying old portion of the level. So, while scrolling I need to make sure to draw new pieces of the level to the back buffer. But before I can do that, I need to figure out which tiles need to get drawn first. And if the person goes 24 pixels to the left, I need to redraw tiles onto the backbuffer and change the offset accordingly as well.
And let's not forget that if the character moves right and there's no more level data to be drawn, there should be no offset but instead the character gets closer to the side of the screen (instead of being centered in the middle of the screen via the X axis).
Basically, I just have a lot of different numbers and values stuck in my mind right now - trying to wrap my head around many concepts and they caused my brain to turn into goo. Anyone have any perspective on how I can approach this?
EDIT: Using VB.Net. C# is applicable as well ( I program in both)
The way the NES did it was with 4 name tables, each 256x240. When you scrolled one off the screen, the adjacent one would scroll on. To get "worlds" bigger than 512x480, you update the name table at the positions that are offscreen.
Generally, a cartridge would have a giant table in ROM with all of the level data, and would track the overall position with 1 or 2 RAM variables. Then when the game scrolled, it would update the RAM variables, use those to lookup the level data table and copy in the new level data into the parts of the name table that were offscreen.
So actually your back buffer should be 512x480, and you only show a 256x240 portion of it.
Have you looked at the disassembly for any NES games that have large scrolling worlds? I think a partial disassembly of Metroid is out there somewhere...
...yeah, found some docs at romhacking.net
Metroid disassembly; not real well commented but with a little effort it shouldn't be too hard to figure it out.
Another disassembly that is commented better.
EDIT: In the 2nd disassembly posted above, look in MetroidGameEnginePage.txt at the "SetupRoom" routine and the "DrawRoom" routine; also the routine at label LEB4D shows how the name table is updated in one case. Also look at the extensive comments above the "GetNameTable" routine. In general, a text search for "name table" throughout the document will get you lots more.
EDIT EDIT: Also at romhacking.net; the memory map for SMB might be useful.
I would set up a grid of image controls and load the levels from a database that stores what column and row each picture is relative to the level. Once the image that represents the game's character gets far enough to the right (you would have to store its location in some module level variables) of the screen you would load the next column of images (while shifting all of the other images one to the left and removing the first column).