Hi Elaine,
Thanks for your help. 
I have changed the model and now it works. The .dx file is #1. 
So I use the command: measure fieldLines #1 lines 500 startAbove 10 color pink linewidth 2. 
The command works but the field lines do not appear.
Is there any problem of the commands?
Qiao Xue

xmgign@126.com
 
From: Elaine Meng
Date: 2018-12-07 00:23
To: xmgign@126.com
CC: chimera-users
Subject: Re: [Chimera-users] Questions about the electric fieldline
Hi Qiao Xue,
Your command looks OK to me, but are you sure that the dx file is model #0?   Check in the Model Panel (open from Favorites menu) that it is really model #0.  If you have other things open at the same time, like the atomic structure, it could be #1, #2, etc. instead and you should change the model number in the command. Other than that, my only other idea is that the dx file is empty or the wrong format.
I hope this helps,
Elaine
-----
Elaine C. Meng, Ph.D.                      
UCSF Chimera(X) team
Department of Pharmaceutical Chemistry
University of California, San Francisco
 
> On Dec 5, 2018, at 11:52 PM, xmgign@126.com wrote:
>
> Hi
> I want to make the electric fieldline but there are always some problems.
> I did this as follows,
> 1. run add charge to the system
> 2. run APBS, the I get the electrostatic surface and a file named 1.dx
> 3. open 1.dx
> 4.measure fieldLines #0 lines 500 startAbove 10 color pink linewidth 2
> then I get the problem : no volume specified
>
> I have check the userguide of measure fieldlines, but there is nothing about the volume.
> measure fieldLines  map-model(s)  [ lines N ] [ startAbove cutoff ] [ step s ] [ modelId model-number ] [ color line-color ] [ lineWidth width ] [ tubeRadius radius ] [ circleSubdivisions M ] [ markers true|false ]
>
> what should I do next?
> Thanks.
> Qiao Xue