https://github.com/hypertidy/quad
Intermediate forms of raster grids
https://github.com/hypertidy/quad
grid mesh quad r raster
Last synced: 18 days ago
JSON representation
Intermediate forms of raster grids
- Host: GitHub
- URL: https://github.com/hypertidy/quad
- Owner: hypertidy
- License: other
- Created: 2017-02-07T04:49:47.000Z (over 9 years ago)
- Default Branch: main
- Last Pushed: 2024-01-10T21:24:33.000Z (over 2 years ago)
- Last Synced: 2024-05-01T13:57:19.572Z (about 2 years ago)
- Topics: grid, mesh, quad, r, raster
- Language: C++
- Homepage: https://hypertidy.github.io/quad/
- Size: 397 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.Rmd
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
Awesome Lists containing this project
README
---
output: github_document
---
```{r, include = FALSE}
knitr::opts_chunk$set(
collapse = TRUE,
comment = "#>",
fig.path = "man/figures/README-",
out.width = "100%"
)
library(anglr)
```
# quad
[](https://github.com/hypertidy/quad/actions/workflows/R-CMD-check.yaml)
The goal of quad is to provide a framework for fleshing out raster-origin mesh geometry when needed.
## Installation
You can install the development version of quad from [GitHub](https://github.com/) with:
``` r
# install.packages("devtools")
devtools::install_github("hypertidy/quad")
```
## Example
This is a basic example which shows you how to expand out the grid when you really need to.
What is a grid? A *raster* is a six-number specification, *dimension* and *extent*.
Let's say we have set of raster data, a matrix in R with *ncols*, *nrows* and an extent.
```{r example}
library(quad)
(dm <- dim(elev)[2:1])
ib <- quad_index(dm)
vb <- quad_vert(dm)
str(ib)
str(vb)
```
That is the basis for building a partly expanded quadmesh, and it is fast.
```{r anglr}
##previous we might have used anglr
system.time(anglr::as.mesh3d(elev))
## what if it was much bigger
el <- elev[seq(1, nrow(elev), length.out = 3600), seq(1, ncol(elev), length.out = 1800)]
system.time(m3d <- anglr::as.mesh3d(el))
str(m3d)
## when we use {quad} we have access to the intermediate steps
system.time({
vb <- quad_vert(c(3600, 1800))
vb <- rbind(matrix(vb, nrow = 2), z = 0.0, h = 1.0)
vb[,1] <- scales::rescale(vb[,1], c(-180, 180))
vb[,2] <- scales::rescale(vb[,2], c(-90, 90))
ib <- matrix(quad_index(c(3600, 1800), ydown = TRUE), nrow = 4L)
## ok still WIP but you see where we're going, anglr needed a
## RasterLayer *object* just to get that extent scaling (!!!), when
## we don't even need an array (it's just dim+extent)
## this is faster and it scales to generic workflows
})
str(vb)
str(ib)
```
## TODO
- [x] Mercury
- [ ] ensure alignment of anglr and quad and control with ydown and comparison to rgl is sane and easy
- [ ] provide flat, matrix, dataframe versions of each output (and compare with {geometries})
- [ ] bridge to {textures} and other packages that are for specific outputs (mesh3d, and various 3D formats, and just plotting with vectorized grid.polygon)
## Code of Conduct
Please note that the quad project is released with a [Contributor Code of Conduct](https://contributor-covenant.org/version/2/1/CODE_OF_CONDUCT.html). By contributing to this project, you agree to abide by its terms.