# Simple viewer of ArcGrid geospatial data written in Haskell
## Synopsis
A simple viewer for ESRI/ArcInfo (ArcGrid) files. A user can pan, zoom and
rotate the rendered dataset with keyboard and mouse (see _Controls_).
The program uses shades of red (by default) normalized by minimum and maximum
value in the VAT of the curent dataset. Black colour represents lower value than
the red one.
## Installation
The program depends on `gloss` and `arcgrid` libraries. The easiest way is to
install utulity `stack` and build the software from the source code.
Currently, as this:
``` sh
$ git clone https://github.com/nbrk/arcgrid.git
$ git clone https://github.com/nbrk/arcgrid-viewer.git
$ cd arcgrid-viewer
$ stack install
# Usually stack will install the program binary in ~/.local/bin .
# You can add it to PATH of you want.
$ ~/.local/bin/arcgrid-viewer ../arcgrid/sample/alps_huge.asc
```
## Usage
The program supports rendering the dataset in few color schemes (red, black and
white, a spectre) in both vector and raster modes.
```
Usage: arcgrid-viewer [OPTION...] <file>
-c MODE --color=MODE color scheme: red|bw|fancy
-r MODE --mode=MODE rendering mode: vector|raster
```
The defaults are to render **in raster** with **red gradient**.
Please keep in mind that big datasets take time and resources to parse and render!
There is some sample `.asc` elevation data from the Alps. It resides in `arcgrid`
library and is [located](https://github.com/nbrk/arcgrid/tree/master/sample) in `arcgrid/sample`.
## Controls
The program uses `gloss` library for rendering and display. Therefore, the
controls are:
```
* Quit
- esc-key
* Move Viewport
- arrow keys
- left-click drag
* Zoom Viewport
- page up/down-keys
- control-left-click drag
- right-click drag
- mouse wheel
* Rotate Viewport
- home/end-keys
- alt-left-click drag
* Reset Viewport
r-key
```
## TODO
- Optimization. The viewer is too damn slow!
- Maybe restrict display only to a selected rectangle.