[GRASSLIST:3114] Re: digitizing and snapping problems

[Kirk R. Wythers]

Hi Jachym,

Did all those things. Here are the values from the custom menue:

    Current SNAPPING threshold (map scale is 1:63360):                    
      |
|         Map : 16.093440  meters.                                       
       |
|         Dig : 0.010000  -  1 / 100.000000 of an inch.                  
       |
|   Enter new Dig threshold or <RETURN> when finished:                   
       |
m----------------------------------------------------------------------- 
------j


If I read this correctly, the snapping distance on the map is 16  
meters, and the threshold is 0.01

And yes, the snapped nodes appear red and the nodes with problems  
appear green (kinda counter intuitive if you ask me... unless red means  
"don't touch it... it's fine"). I think what I'm looking for is a way  
to keep nodes active after a polygon snaps has been closed. That way  
you can come back and start a second polygon off the node from the side  
of the first polygon (thereby sharing a side).

Kirk

On Apr 7, 2004, at 2:05 PM, Jachym Cepicky wrote:

> Hullo,
>
> first you have to set your Map's scale to (in the Information screen -
> the first screen after you select the vector file name) some other
> value, than 1:1. Than
> you have to go to Costumise Menu and set the snapping threshold. In
> GRASS, the snapping value is in meters and you will get it thrue the
> snapping threshold
>
> Try something like this:
>
> Map's scale             Reasonable snapping      Snapping thrashold
>                         distance
> 1:5 000 to 1:10000       1 to 2 m                0.0017 to 0.002
> 1:10 000 to 1:25 000     2-5 m                   0.002 to 0.008
> 1:25 000 to 1:50 000     5-10 m                  0.008 to 0.017
>
>
> The snapped nodes appear red (usually).
>
> I hope, I have expresed my self.
>
> Jáchym
> On Wed, Apr 07, 2004 at 12:46:09PM -0500, Kirk R. Wythers wrote:
>> I seem to be going though several extra steps in order to get polygons
>> to close without undershoot/overshoots. I am hoping that someone will
>> be able to point out a more expedient procedure.
>>
>> My problem is this: When digitizing common area boundaries, I am  
>> having
>> a hard time getting a new line/area to snap to the line of the  
>> existing
>> polygon (even when I try intentionally to start the new line off of an
>> existing corner when a node should be). The first node of my new line
>> is well within my snap threshold, but does not snap.
>>
>> I can go back "after the fact", and use "Edit/Break" function to  
>> insert
>> a new node on the first polygon, then use "Edit/Snap" to connect the
>> lines. However, this is time consuming and I was hoping that someone
>> would point out a technique to get the new line to snap to the fist
>> polygon in the first place. Once I complete the first polygon the
>> polygon's nodes seem to disappear. So that by the time I start the  
>> line
>> to close the second polygon, there doesn't seem to be a node to snap
>> to, just a angle where the node "used to be?".
>>
>> Thanks,
>>
>> Kirk
>>
>> ---------------------------------------------------------------------- 
>> --
>> Kirk R. Wythers	                                    tel: 612.625.2261
>> Dept. of Forest Resources                fax: 612.625.5212
>> University of Minnesota     email: kwythers at umn.edu
>> ---------------------------------------------------------------------- 
>> --
>>
>
> -- 
> Jachym Cepicky
> e-mail: jachym.cepicky at centrum.cz
> URL: http://les-ejk.cz
>
------------------------------------------------------------------------
Kirk R. Wythers	                                    tel: 612.625.2261
Dept. of Forest Resources                fax: 612.625.5212
University of Minnesota     email: kwythers at umn.edu
------------------------------------------------------------------------