crs | A | REST library

EDIT: I have changed the question to new code that produces the same error and is more reliable in doing so.

I have been struggling to find a segmentation fault in my code for a while now and have boiled it down to the following code:

Some people working on a the construction site use a local custom coordinate system. I have been given a proj4 string like this:

+proj=omerc +lat_0=46.325454996 +lonc=7.99050231 +alpha=60.4026421358 +gamma=90 +k=1 +x_0=350 +y_0=200 +datum=WGS84 +units=m +no_defs +type=crs

And x,y coordinates like this 429.079425606807, 261.126436507318

And I need to convert their coordinates into WGS84 and back

I tried to use the DotSpatial to make the transformation. Any other libraries in C# can be accepted.

To get a circular subset of a las-dataset with specific area, I would like to use lidR::clip_circular(). To do so, I first calculate the central point of my las-dataset, then I define the radius I want to use, to get a subset of exactly 500m^2 from the centroid of my las-dataset. The operation works and does not throw any error, the result however is not correct, see base::print() at the end of my short code snippet.

I have tried to use lidR::clip_roi() as well, providing a polygon representing my region of interest, but got the same, incorrect result. Now I do not have any clue how to go on. I could imagine, that it is about the crs I am using (EPSG:25832) or because the area is circular and not rectangular...

I’m getting angry about something that seems simple to me. I would like to select the points inside a polygon with the sf package. Both have the same CRS : EPSG:27572 "NTF (Paris) / Lambert zone II. I can't provide a reproductible example because data are confidential...

My points :

I'm trying to create grids inside the boundary of Suffolk County, NY whose class is "sf". I named the layer "SUFF". Through using st_area(SUFF), I got to know that the area of the county is 6136105813 square meter.

So, I decided to create the rectangular grid with the size of 500 meter * 500 meter. I wrote the code: fishnet <- st_make_grid(st_transform(SUFF, crs=st_crs(4326)),cellsize = 500, square = TRUE) %>% st_sf().

However, I only got one grid. Fishnet for cellsize = 500 And then I tried many different cell size values and I found that I would got 1 grid if cellsize >= 1, 4 grids if cellsize = 0.5, 32 grids if cellsize = 0.25... Fishnet for cellsize = 0.25

In my understanding, the unit of the cell size should be the same as the SUFF layer, which is meter, is that correct? Would you mind giving me some guidance that how I can create 500m * 500m grids by using st_make_grid()?

I have a large set of coordinates from the critical and endangered habit federal registry. I'm trying to digitize these maps for analysis. Here's a sample of the data as an example.

There are some other posts out there related to this one, such as these: Post 1, Post 2, Post 3. However, none of them deliver what I am hoping for. What I want is to be able to draw a line segment from a specific point (a sampling location) to the edge of a polygon fully surrounding that point (a lake border) in a specific direction ("due south" aka downward). I then want to measure the length of that line segment in between the sampling point and the polygon edge (really, it's only the distance I want, so if we can get the distance without drawing the line segment, so much the better!). Unfortunately, it doesn't seem like functionality to do this already exists within the sf package: See closed issue here.

I suspect, though, that this is possible through a modification of the solution offered here: See copy-pasted code below, modified by me. However, I am pretty lousy with the tools in sf--I got as far as making line segments that just go from the points themselves to the southern extent of the polygon, intersecting the polygon at some point:

I'd like to create polygons with st_voronoi and merge them by a variable