raster | C library for geographical raster data analysis | File Utils library
kandi X-RAY | raster Summary
kandi X-RAY | raster Summary
The Pronto Raster Library is a C++ library to work with raster data. The core idea of the library is to make raster data accessible following the Range concept, making it possible to work with them using standard and modern C++ idioms. The library makes it straightforward to implement Map Algebra operations, including Moving Window analysis.
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QUESTION
I have a doubt trying to understand and use glBitmap function. I started from this example and trying to draw a 40x40 "bitmap" and avoiding a situation like this I tried this:
...40 x 40 is 1600 bits -> so I need 200 bytes of info (1600/8)
ANSWER
Answered 2021-Jun-14 at 10:38You missed to set the alignment. By default OpenGL assumes that the start of each row of the raster is aligned to 4 bytes. This is because the GL_UNPACK_ALIGNMENT
parameter by default is 4. Each row in the raster has 5 bytes (40 / 8 = 5). Therefore you need to change the alignment to 1:
QUESTION
I need to project longitude/latitude coordinates in the terra package, but I don't believe it is working correctly, as I am trying to extract data from a raster with this projection, but the data is not being extracted correctly.
Here's my lon/lat points and the code I am using to try to project them.
...ANSWER
Answered 2021-Jun-13 at 18:23Why do you think it has to do with the projection? Either way, it appears to work for me.
QUESTION
I am using a 3.5: TFT LCD display with an Arduino Uno and the library from the manufacturer, the KeDei TFT library. The library came with a bitmap font table that is huge for the small amount of memory of an Arduino Uno so I've been looking for alternatives.
What I am running into is that there doesn't seem to be a standard representation and some of the bitmap font tables I've found work fine and others display as strange doodles and marks or they display upside down or they display with letters flipped. After writing a simple application to display some of the characters, I finally realized that different bitmaps use different character orientations.
My questionWhat are the rules or standards or expected representations for the bit data for bitmap fonts? Why do there seem to be several different text character orientations used with bitmap fonts?
Thoughts about the questionAre these due to different target devices such as a Windows display driver or a Linux display driver versus a bare metal Arduino TFT LCD display driver?
What is the criteria used to determine a particular bitmap font representation as a series of unsigned char values? Are different types of raster devices such as a TFT LCD display and its controller have a different sequence of bits when drawing on the display surface by setting pixel colors?
What other possible bitmap font representations requiring a transformation which my version of the library currently doesn't offer, are there?
Is there some method other than the approach I'm using to determine what transformation is needed? I currently plug the bitmap font table into a test program and print out a set of characters to see how it looks and then fine tune the transformation by testing with the Arduino and the TFT LCD screen.
My experience thus farThe KeDei TFT library came with an a bitmap font table that was defined as
...ANSWER
Answered 2021-Jun-12 at 16:19Raster or bitmap fonts are represented in a number of different ways and there are bitmap font file standards that have been developed for both Linux and Windows. However raw data representation of bitmap fonts in programming language source code seems to vary depending on:
- the memory architecture of the target computer,
- the architecture and communication pathways to the display controller,
- character glyph height and width in pixels and
- the amount of memory for bitmap storage and what measures are taken to make that as small as possible.
A brief overview of bitmap fonts
A generic bitmap is a block of data in which individual bits are used to indicate a state of either on or off. One use of a bitmap is to store image data. Character glyphs can be created and stored as a collection of images, one for each character in the character set, so using a bitmap to encode and store each character image is a natural fit.
Bitmap fonts are bitmaps used to indicate how to display or print characters by turning on or off pixels or printing or not printing dots on a page. See Wikipedia Bitmap fonts
A bitmap font is one that stores each glyph as an array of pixels (that is, a bitmap). It is less commonly known as a raster font or a pixel font. Bitmap fonts are simply collections of raster images of glyphs. For each variant of the font, there is a complete set of glyph images, with each set containing an image for each character. For example, if a font has three sizes, and any combination of bold and italic, then there must be 12 complete sets of images.
A brief history of using bitmap fonts
The earliest user interface terminals such as teletype terminals used dot matrix printer mechanisms to print on rolls of paper. With the development of Cathode Ray Tube terminals bitmap fonts were readily transferable to that technology as dots of luminescence turned on and off by a scanning electron gun.
Earliest bitmap fonts were of a fixed height and width with the bitmap acting as a kind of stamp or pattern to print characters on the output medium, paper or display tube, with a fixed line height and a fixed line width such as the 80 columns and 24 lines of the DEC VT-100 terminal.
With increasing processing power, a more sophisticated typographical approach became available with vector fonts used to improve displayed text quality and provide improved scaling while also reducing memory required to describe the character glyphs.
In addition, while a matrix of dots or pixels worked fairly well for languages such as English, written languages with complex glyph forms were poorly served by bitmap fonts.
Representation of bitmap fonts in source code
There are a number of bitmap font file formats which provide a way to represent a bitmap font in a device independent description. For an example see Wikipedia topic - Glyph Bitmap Distribution Format
The Glyph Bitmap Distribution Format (BDF) by Adobe is a file format for storing bitmap fonts. The content takes the form of a text file intended to be human- and computer-readable. BDF is typically used in Unix X Window environments. It has largely been replaced by the PCF font format which is somewhat more efficient, and by scalable fonts such as OpenType and TrueType fonts.
Other bitmap standards such as XBM, Wikipedia topic - X BitMap, or XPM, Wikipedia topic - X PixMap, are source code components that describe bitmaps however many of these are not meant for bitmap fonts specifically but rather other graphical images such as icons, cursors, etc.
As bitmap fonts are an older format many times bitmap fonts are wrapped within another font standard such as TrueType in order to be compatible with the standard font subsystems of modern operating systems such as Linux and Windows.
However embedded systems that are running on the bare metal or using an RTOS will normally need the raw bitmap character image data in the form similar to the XBM format. See Encyclopedia of Graphics File Formats which has this example:
Following is an example of a 16x16 bitmap stored using both its X10 and X11 variations. Note that each array contains exactly the same data, but is stored using different data word types:
QUESTION
I'm new to the package stars
for R
and am trying to do basic spatial operations with curvilinear data. I am using netCDF climate data. I am able to read the netcdf into r along with a shapefile I would like to use to specify the area in which I want to conduct analyses. I have tried to crop the file directly using st_crop()
but receive the following error:
ANSWER
Answered 2021-Jun-10 at 18:11Well I figured it out and it was quite simple. I was able to subset the stars object using the shapefile with this simple code: test[wrst]
. No warping or resampling necessary.
QUESTION
I'd like to create shapefile files in Shiny. A create the files corrected in tempdir()
, including the final *zip
file. But the output error is Error in h: error evaluating argument 'x' in method selection for function 'unique': 'cannot find function "selectedvariable0"'[No stack trace available]
Ok, work with reactive
objects is necessary to be careful, but despite I try to use selectedvariable0()$ID_UNIQUE
,selectedvariable0()
or output$selectedvariable0
. Nothing working for me. In my example:
ANSWER
Answered 2021-Jun-10 at 12:59Now add zip
library and remove for not create "/" for not create path confusion:
QUESTION
I am using a code written by Victor Velasquez to extract data from raster files which contain dayly precipitation data since 1981. When I run the code, I get this error that some index is out of bounds. I did a little research and found that this is common and there are a lot of similar questions here, but I haven´t been able to find the specific solution for this case.
The error:
...ANSWER
Answered 2021-Jun-09 at 13:29It looks like the file you are reading does not contain the geospatial point you are trying to find data for. (If this is incorrect please let me know).
You can add a statement to catch if a point is contained in the data:
QUESTION
I am trying to get some elevations for bird locations I have in NZ. I thought I might use the code provided as an answer to a similar question (Extracting elevation from website for lat/lon points in Australia, using R), unfortunately I get errors when using the extract function in the raster package, even though the code is almost identical.
...ANSWER
Answered 2021-Jun-08 at 07:11I don't know exactly why, but the subtle reason is that, compared to Australia, getData
returns a different data structure for New Zealand. It returns a list, where the RasterLayers are in the first (and second) list element:
QUESTION
I'm trying to manage large datasets or files (e.g., GeoTIFF) on plain R (via terminal) or RStudio (1.4.1106), but both apps crash every time on Linux (Manjaro, x64, core i7, and 8 GB RAM) for some scripts (especially when a raster data is plotted using ggplot2 to produce a high-quality map, as well as a lmer function with random factors using a csv file with ~3000 rows and 6 columns). Probably the issue refers to memory management since all the memory is consumed. To overcome, I tried two packages to limit/increase the memory size, such as "unix" and "RAppArmor". However, if the memory size is limited, all your available RAM was exhausted and the famous message "cannot allocate a vector..." is shown. On the other hand, if the memory size is increased to high levels, R/RStudio simply crashes. On Windows, the following code works like a charm to increase memory size (only needed to plot a raster into ggplot2):
...ANSWER
Answered 2021-Jun-08 at 02:15With the help of a member from another forum (https://community.rstudio.com/t/out-of-memory-on-r-using-linux-but-not-on-windows/106549), I found the solution. The crash was a result of memory limitation in the swap partition, as speculated earlier. I increased my swap from 2 Gb to 16 Gb and now R/RStudio is able to complete the whole script. It is a quite demanding task since all of my physical memory is exhausted and nearly 15 Gb of the swap is eaten.
QUESTION
Sorry for the evidently stupid question I haven't be able to solve, even after googleing for a while. Let's suppose the following situation, where I have two rasters with overlapping but different value ranks.
...ANSWER
Answered 2021-Jun-07 at 16:06Based on the answer I shared in the previous comment, you can manually set the breaks of the legend and the colors. Then you just need to apply that color ramp to both plots. Here's the code and the plot.
QUESTION
I'm working on a habitat occupancy prediction encompassing the entire state of Wyoming. Certain site covariate rasters work in the prediction while others with matched resolution, extent, etc. do not.
A short reproduceable example of my code is below. After extensive troubleshooting I've found I have 3 rasters of the 5 I need to use that cause this script to fail, all with the same error. I'm assuming my rasters have somehow become corrupted(?) but wanted to see if anyone has another idea on what could be happening.
Data is at this link. The data is the unmarked object (saved as .rds) and 2 very small clips off of: 1. the raster that works, and 2. one of the rasters that does not work
Steps I took to originally align the rasters for stacking - for information purposes ...ANSWER
Answered 2021-Jun-07 at 08:27Answer
The error arises because you have missings in sNoJoy
. Had those not been missing, it would have worked just fine.
Question rewritten
Your problem has nothing to do with your parallel code. It boils down to this:
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