As part of my software I have to somehow convert and display Esri ASCII (.asc) files on a leaflet map.
The files are in the filesystem and the backend is in nodeJS.
.asc is a raster format and gdal_translate manages to translate the files as I like. Unfortunately I can't use GDAL in node and as far, as I see it, gdal-node is not able to convert the files. Manually converting files is not an option.
My data is always somehow geo referenced, so if I get an image, it has to be placed on the right spot on the worldmap.
Help would be highly appreciated, because I feel kinda overwhelmed by all this GEO stuff.
If you want the normal set of features Leaflet offers, like zooming, what you need is called a map tile service.
There are a few map tile standards that Leaflet supports. Generally though, making map tiles is complicated — particularly if your ASCII grids are in lat/long but you're using a background layer from Google, Bing, OSM that's in "web Mercator" — so you probably don't want to write one in Node yourself.
Look at GeoServer and see if that will fit into your setup.
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I just started at a new company and have been asked to do what I believe impossible, but I need confirmation on this. The website that my company has allows users to view images in extremely high resolution using SVGs. We've built a custom viewer for these images that allow you to zoom and scroll around the image and it works well. Because of this, the image format "needs" to remain SVG. However, we need to include a watermark to this image. The way we're doing this right now is passing the SVG and PNG watermark to the client, inserting the watermark into the SVG, and displaying it to the user. This is very obviously easily hacked as anyone with client-side experience knows (The dev team here is mostly older developers and don't have much web experience). Even if the raw SVG isn't intercepted, they can still just delete the watermark from the source. I've convinced my boss to make the watermark be injected on the server-side, so this leaves just the problem that SVGs are editable by the end-client.
What I want to know is if one of these two things are possible:
1) Is there another image format akin to SVG that could be used to keep this highly scalable image without loosing resolution, and without it being directly editable by an end-client? The only options that people seem to discuss for the web is JPG, GIF, PNG, and SVG. I've looked at Adobe Illustrator ".ai" files and EPS (Encapsulated PostScript) as other vector options, but I can't find anywhere if I can modify these images in PHP, which is key if I want to overlay a watermark in server-side code.
2) Is there a way to obfuscate the raw SVGs content so that the use can't go and manipulate it? I've seen SVGs that have <image ...> tags inside them with PNGs represented as long and complex strings before. Something like xlink:href="data:image/png;base64...". I was wondering if there's a way to display an SVG as this string, so that the data can't be directly manipulated. I'm sure there's an algorithm to reverse these, but so long as we're sticking with SVGs, I need to make this as secure as possible with as many hoops to jump through as possible if someone wants to steal the data.
Either way would be acceptable, as long as removing this watermark is more complex than just hitting F12 and removing the element inside the dev tools.
Is there another image format akin to SVG that could be used to keep this highly scalable image without loosing resolution, and without it being directly editable by an end-client?
SVG is a vector format, and to maintain extreme scalability, you need to stick with vectors, be it any format. However, in that case it will always be possible to remove the vectors that belong to your watermark. There are of course vector formats that are stored as binary, which would make it somewhat harder for an enduser to parse and edit, but those are not editable in PHP either, and are much less compatible. So you probably don't want to do this.
Is there a way to obfuscate the raw SVGs content so that the user can't go and manipulate it?
First, it will never be "secure" in the sense that as said above, it will always be possible to remove the watermark from a vector image. (Btw the only difference to bitmap formats like JPG is that content below the watermark in bitmap is actually missing, while in SVG it's still there.)
However, depending on how "good" you want this to be, you can do a few things. I think the "goodness" here means the effort needed to remove the watermark, and you can raise the bar relatively easily. You don't have to (and you probably can't reasonably) obfuscate the whole SVG.
One thing that comes to mind is that SVG is basically just XML, it consists of tags like <rect>, <line>, <circle> etc. The order of these tags doesn't matter much (mostly, with exceptions of course). So you could entwine the tags that draw your watermark pretty much randomly among existing tags. I mean really randomly, so different downloads would produce different results. If you do this well (eg. you find line tags to "hide" your watermark line tags, and so on), it will be hard to automatically remove the watermark, because it's all over relevant data that is your actual image. Of course, the watermark could still be visually in a corner, and this is already a weakness, anything drawn to a corner could possibly be removed automatically. And it will be easy to remove by hand with any decent editor I suppose. So it depends on what the purpose is.
But I still think this sort of thing could make it hard enough in many scenarios (and would be totally inadequate in others).
I am looking for the best approach for generating images of text on the server side (preferably Node.js). It will need to accommodate things like paging (so generating multiple images of text for one text input if it is too long to fit on one page). I am looking for something that is fairly precise and allows for a good deal of type configuration.
I have looked at a few options:
Use Canvas. This approach would work for most of the use cases. I could use a text engine like textjs for the layout. However, this is somewhat limiting as Canvas doesn't have specific text metrics (for things like text height used for exact positioning). This could make paging difficult.
Use normal HTML with something like PhantomJS to generate and them capture an image of the text. While this approach will work for some use cases, it makes it hard to handle things like paging.
Use some other text engine. I've looked around and found some options - but it would need to be something that I could call from Nodejs (as I'll likely use this on AWS Lambda).
What would you recommend?
I lately did something very similar - also with node.js on Lambda. In my opinion the best approach is using PhantomJS and maybe taking the detour of generating a PDF.
With HTML and CSS you can conveniently style the output exactly how you want it, which is a great advantage about the way more complicated Canvas approach. You only have to take care of adding some horizontal space wherever you expect the pagebreak (of course this depends on your usecase and may not be necessary). Having the rendered HTML page you now have two options:
You could generate a PDF - which will take care of generating multiple pages - and then rasterize that to images
Or you directly generate an image with Screen Capture (example Code) and then splitt that image horizontally
Both approaches worked fine for me.
I am writing a program that will output 3D model files based on simple geometric shapes (e. g. rectangular prisms & cylinders) with known coordinates in 3-dimensional space. As an example, imagine creating a 3D model of stonehenge. this question suggests that OBJ files are the easiest to generate, but I'm struggling to find a good tutorial or easy-to-use library for doing so.
Can anyone either
(1) describe step-by-step how to create a simple file OR
(2) point me to a tutorial that describes how to do so
Notes:
* Using a GUI-based program to draw such files is not an option for me
* I have no prior experience with 3D modeling
* Other formats such as WRL or DAE would work for me as well
EDIT:
I do not need to use textures, just combinations of simple geometric shapes positioned in 3D space.
I strongly recommend to use some ASCII exchange format there are many out there I usually use these:
*.x DirectX object (it is a C++ source code)
this one is easiest to implement !!! But there are not many tools that can handle them. If you do not want to spend too much time coding then this is the right choice. Just copy the templates (at the start) from any *.x file to get started.
here some specs
*.iges common and importable on most CAD/CAM platform (Catia included)
this one is a bit complicated but for export purposes it is not that bad. It supports Volume operation like +,-,&,^ which are VERY HARD to implement properly but you do not have to use them :)
*.dxf AutoCAD exchange format
this one is even more complicated then IGES. I do not recommend to use it
*.ac AC3D
I first saw this one in flight gear.
here some specs
at first look it is quite easy but the sub-object implementation is really tricky. Unless you use it you should be fine.
This approach is easily verifiable in note pad or by loading to some 3D model viewer. Chose one that is most suitable for your needs and code save/load function to your Apps internal model class/struct. This way you will be compatible with other software and eliminate incompatibility problems which are native to creating 'almost known' binary formats like 3ds,...
In your case I would use IGES (Initial Graphics Exchange Specification)
For export you do not need to implement all just few basic shapes so it would not be too difficult. I code importers which are much much more complicated. Mine IGES loader class is about 30KB of C++ source code look here for more info
You did not provide any info about your 3D mesh model structure and capabilities
like what primitives you use, are your object simple or in skeleton hierarchy, are you using textures, and more ... so it is impossible to answer
Anyway export often looks like this:
create header and structure of target file format
if the format has any directory structure fill it and write it (IGES)
for sub-objects do not forget to add transformation matrices ...
write the chunks you need (points list, faces list, normals, ...)
With ASCII formats you can do this inside String variable so you can easily insert into or modify. Do all thing in memory and write the whole thing to file at the end which is fast and also add capability to work with memory instead of files. This is handy if you want to pack many files to single package file like *.pak or send/receive files through IPC or LAN ...
[Edit1] more about IGES
fileformat specs
I learned IGES from this pdf ... Have no clue where from I got it but this was first valid link I found in google today. I am sure there is some non registration link out there too. It is about 13.7 MB and original name IGES5-3_forDownload.pdf.
win32 viewer
this is free IGES viewer. I do not like the interface and handling but it works. It is necessary to have functional viewer for testing yours ...
examples
here are many tutorial files for many entities there are 3 sub-links (igs,peek,gif) where you can see example file in more ways for better understanding.
exporting to IGES
you did not provide any info about your 3D mesh internal structure so I can not help with export. There are many ways to export the same way so pick one that is closest to your App 3D mesh representation. For example you can use:
point cloud
rotation surfaces
rectangle (QUAD) surfaces
border lines representation (non solid)
trim surface and many more ...
for a university project I have to compute a 3D mesh, then display it.
By mesh I mean a list of triangles, where each point has a specific elevation.
What is the easiest tool that exists both on windows and linux that would allow me to display such a mesh?
I just want to be able to visualize the mesh and rotate it, and I can code any specific mesh format needed to be used as an input.
What I mostly want is a tool that is easy to install for the final user of my program.
Almost every tool reads the .obj format, for example MeshMan, MeshLab and ArtOfIllusion. They all work under Windows and Linux. Geomview (.off-Files) is also great, but hard to install under Windows.
I'm using for this purpose osgviewer from OpenSceneGraph
I wouldn't know about the easiest tool, but have you tried Blender? It's cross platform.
There are some standard file formats for triangle meshes. Try outputing to .ply file and using one of the existing viewers for that.
I tend to use VTK file formats since I work in scientific visualization; that would be overkill for you.
In fact, I wrote a VTK/QT based app for viewing meshes that can handle .ply files https://github.com/HalCanary/vtkviewer.
Im writing a game engine and I'm wondering what 3D model format should I use/load/export? Obj seems universal and easy but it also appears to be unreliable in that most models out there contain errors and it doesn't store anywhere near as much as other formats.
There appear to be formats specifically for games such as MD2/3/5 but Im not sure, I use wings3d if I model, and I don't know what other details beyond purely loading what I need and support from the format Id have to implement, such as would I need to implement IK? and can I use scripted per piece animation rather than Inverse kinematics and bone rigging?
Collada is an open XML based format for 3d models owned by the Khronos group(OpenGL standards body)
From the Collada.org FAQ:
The COLLADA 1.4.x feature set includes:
Mesh geometry
Transform hierarchy (rotation, translation, shear, scale, matrix)
Effects
Shaders (Cg, GLSL, GLES)
Materials
Textures
Lights
Cameras
Skinning
Animation
Physics (rigid bodies, constraints, rag dolls, collision, volumes)
Instantiation
Techniques
Multirepresentations
Assets
User data
Before worrying about what 3D formats you want to support, I think you should really focus on what features you are planning to implement in your engine. Write those down as requirements, and pick the format that supports the most features from the list... as you'll want to showcase your engine (I am assuming you are planning for your engine to be publicly available). You might even want to roll your own format, if your engine has specific features (which is always a good thing to have for a game engine).
After that, support as many of the popular formats as you can (.X, .3DS, .OBJ, .B3D)... the more accessible your engine is, the more people will want to work with it!
Collada is a nice and generic format, but like Nils mentions, it is not an ideal format for final deployment.
I use my own binary format. I've tried to use existing formats but always run into limitations. Some could be worked around, others where showstoppers.
Collada may be worth a look. I don't think that it's that good as a format to be read by a 3D engine. It's fine as a general data-exchange format though.
http://www.collada.org/mediawiki/index.php/Main_Page
+1 for Collada. You may also want a custom native binary format for really fast loading (usually just a binary dump of vertex/index buffer data, plus material and skeleton data, and collision data if appropriate).
One trend in the games industry is to support loading a format like collada in the developer build of the engine, but also have a toolchain that exports an optimized version for release. The developer version can update the mesh dynamically, so as artists save changes, the file is automatically reloaded allowing them an (almost) instant WYSIWYG view of their model, but still providing a fully optimised release format.
support Collada well, and then supply good converters to/from the other formats (this might be the hard part). This will give you maximum flexibility. Take a look at C4 engine
Collada is great, but it lives more on the 3D app side of things. ie it's best used for transferring 3D data between applications, not loading 3D data from within a games engine. Have you looked into Lua? It's widely used in games because its a scripting language that's both ridiculously quick (perfect for games) and very flexible (can be used to represent whatever data you need for your engine).