Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

2017-03-30 16:02 GMT-06:00 Rich Shepard : > On Thu, 30 Mar 2017, Laurent C. wrote: > >> In that case, you will not see the accumulation upstream the culvert that >> should normally occur if the pipe is actually higher than the ground. > > > Laurent, > > Both invert and

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Thu, 30 Mar 2017, Laurent C. wrote: In that case, you will not see the accumulation upstream the culvert that should normally occur if the pipe is actually higher than the ground. Laurent, Both invert and outfall are above ground level and below the road. If r.carve used the mean

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

2017-03-30 12:38 GMT-06:00 Rich Shepard : > On Thu, 30 Mar 2017, Laurent C. wrote: > >> You can create a new vector map and create a line that link the two >> points. However, r.carve will interpolate the elevation between the start >> point and the end point. > > >

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Thu, 30 Mar 2017, Laurent C. wrote: You can create a new vector map and create a line that link the two points. However, r.carve will interpolate the elevation between the start point and the end point. Laurent, If my visual interpretation of the output (detail of culvert attached) is

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Thu, 30 Mar 2017, Laurent C. wrote: You can create a new vector map and create a line that link the two points. However, r.carve will interpolate the elevation between the start point and the end point. Laurent, Have this line in a vector map called 'stream.' If you culvert invert

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Thu, 30 Mar 2017, Laurent C. wrote: You need first to create a new vector map (or edit an existing one) and select "digitize new line". Laurent, Oh. Didn't notice the combo box on the extreme left side. Sigh. Thanks, Rich ___ grass-user

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

2017-03-30 12:09 GMT-06:00 Rich Shepard : > On Thu, 30 Mar 2017, Rich Shepard wrote: > >> Would the process be to use v.edit on a copy (called 'stream') of the >> culvert point map to generate a straight line between the two points? That >> would provide the vector input

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

2017-03-30 12:00 GMT-06:00 Rich Shepard : > On Thu, 30 Mar 2017, Laurent C. wrote: > >> If you want to 'open' the culvert, you'll have to cut through the road. >> You can do this with r.carve, for example. > > > Certainly worth doing. The r.carve manual page requires as

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Thu, 30 Mar 2017, Rich Shepard wrote: Would the process be to use v.edit on a copy (called 'stream') of the culvert point map to generate a straight line between the two points? That would provide the vector input r.carve wants. How do I add a line between two specific points using the

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Thu, 30 Mar 2017, Laurent C. wrote: If you want to 'open' the culvert, you'll have to cut through the road. You can do this with r.carve, for example. Certainly worth doing. The r.carve manual page requires as input a vector map containing streams. Having only two points (culvert inlet

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

Rich, If I understand well, you have a 'raw' DEM and you want to open the culvert in that DEM. If it is an under-road culvert, your 'raw' DEM will show the road elevation, and the culvert will not be shown. i.e the culvert is blocked. If you want to 'open' the culvert, you'll have to cut through

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Thu, 30 Mar 2017, Rich Shepard wrote: Germane to what Markus M. wrote, "The point locations used to edit the original DEM are probably wrong (not close to the center), ..." I now think that's where I made one mistake. Nope. I zoom in to isolate those 4 cells in in the blocked map. No

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Thu, 30 Mar 2017, Nikos Alexandris wrote: For the record: there is a "differences" color table which is useful for this. Don't forget to try r.colors with -e or -a -g if the first attempt does not show much differences. I _had_ not noticed the 'differences' color table. Applying that

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Thu, Mar 30, 2017 at 2:46 AM, Rich Shepard wrote: > > On Wed, 29 Mar 2017, Vaclav Petras wrote: > >> As Soeren mentioned in the other part of the thread, use r.univar to get >> the statistics. Don't rely on just looking at the resulting raster map. >> There can be

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Wed, Mar 29, 2017 at 8:46 PM, Rich Shepard wrote: > n=140652 > null_cells=71271 > cells=211923 > Relatively hight number of null cells. > min=-1.89342188835144 > max=0.00093058729544282 > range=1.89435247564688 > Probably small differences, but there is at least

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

Rich Shepard wrote: No differences? Wrong syntax? GRASS hung due to an initial syntax error; corrected. Now I have the difference map which is a solid color using the elevation color table. Ergo, no differences. Moritz: For the record: there is a "differences" color table which is

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Wed, 29 Mar 2017, Vaclav Petras wrote: As Soeren mentioned in the other part of the thread, use r.univar to get the statistics. Don't rely on just looking at the resulting raster map. There can be things like outliers which may throw the visualization off. Vaclav, Here are the results

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Tue, Mar 28, 2017 at 4:30 PM, Rich Shepard wrote: > Now I have the difference map which is a solid color... > ...Ergo, no differences. > As Soeren mentioned in the other part of the thread, use r.univar to get the statistics. Don't rely on just looking at the

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On 28/03/17 22:30, Rich Shepard wrote: On Tue, 28 Mar 2017, Rich Shepard wrote: No differences? Wrong syntax? GRASS hung due to an initial syntax error; corrected. Now I have the difference map which is a solid color using the elevation color table. Ergo, no differences. For the

Re: [GRASS-user] r.mapcalc: compare two maps [RESOLVED]

On Tue, 28 Mar 2017, Rich Shepard wrote: No differences? Wrong syntax? GRASS hung due to an initial syntax error; corrected. Now I have the difference map which is a solid color using the elevation color table. Ergo, no differences. Rich ___