Document:

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                                                                   EXHIBIT 10.50

                        AMENDED AND RESTATED STOCK OPTION

         THIS CERTIFIES THAT, FOR VALUE RECEIVED, Invisa, Inc., a Nevada
corporation ("Invisa, Inc." or the "Company") has, on November 8, 2002, granted
to G.M. Capital Partners Ltd. ("Holder") the right and option until December 31,
2005 to purchase 500,000 shares of Common Stock of Invisa, Inc., at a purchase
price of $3.50 per share.

         The Company commits that it will, on one occasion during the term of
this Option, cause the shares covered by this Option to be registered under the
Securities Act of 1933 (the "Act"), in accordance with the following: (i) the
cost of any such Registration Statement shall be borne solely by the Company
provided that the Company shall not be required to pay any commissions, legal
fees or other sales cost incurred by the Holder; (ii) commencing on January 1,
2004, Holder shall have the right to demand that the Company file and exercise
reasonable efforts to effect a Registration Statement under the Act covering
250,000 shares which may be purchased under this Option unless 250,000 shares
which may be purchased under this Option have previously been registered under
the Act by the Company; and (iii) commencing on July 1, 2005, Holder shall have
the additional right to demand that the Company file and exercise reasonable
efforts to effect a Registration Statement under the Act covering the remaining
250,000 shares which may be purchased under this Option unless the Company has
previously registered all 500,000 shares which may be purchased under this
Option. Such demand to register under subparagraph (ii) and under subparagraph
(iii) shall be in writing, executed by G.M. Capital Partners Ltd. and shall
state Holder's intention to exercise the Option to purchase the shares demanded
to be registered.

         In the event of a stock dividend or stock split resulting in the number
of outstanding of shares of the Company being changed, the applicable exercise
price and number of shares, as provided in this Option, shall be proportionately
adjusted. In the event of the merger, consolidation, or combination of the
Company into another company or entity which survives that transaction, the
shares which may be purchased under this Option shall be converted into an
equivalent number of shares of the surviving entity. In the event of the sale of
all or substantially all of the assets of the Company, the shares which may be
purchased upon the exercise of the Option shall be treated in any distribution
as if said shares are issued and outstanding, with the exception that the
exercise price under this Option shall be deducted from the amount to be
distributed on a per-share basis.

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                                                                               2

         The grant of this Option is made without registration under the Act by
reason of a specific exemption. The Option and shares to be issued at exercise
shall (unless registered in accordance with this Option) be restricted as to
transfer in accordance with Rule 144 of the Act.

         As a condition to the issuance of shares of Common Stock of the Company
under this Option, the Holder agrees to remit to the Company at the time of any
exercise of this Option any taxes required to be withheld by the Company under
Federal, State, or Local law as a result of the exercise of this Option.

         This Option may not be transferred without the consent of the Company.

         The Holder shall not have any of the rights of a shareholder with
respect to any shares of the Company's common stock until the purchase price for
the shares has been paid to the Company.

         THIS AMENDED AND RESTATED OPTION AGREEMENT AMENDS AND RESTATES THE
OPTION AGREEMENT BETWEEN THE COMPANY AND THE HOLDER FOR THE MAY 7, 2002 GRANT OF
THE RIGHT AND OPTION UNTIL JUNE 30, 2004 TO PURCHASE 500,000 SHARES OF THE
COMPANY'S COMMON STOCK AT A PURCHASE PRICE OF $5.50 PER SHARE (THE "MAY 7, 2002
OPTION"). THIS AMENDED AND RESTATED OPTION SUPERSEDES AND REPLACES, IN ITS
ENTIRETY, THE MAY 7, 2002 OPTION WHICH THE COMPANY AND THE HOLDER HEREBY
ACKNOWLEDGE AND AGREE IS CANCELLED BY THE PARTIES' EXECUTION OF THIS AMENDED AND
RESTATED OPTION, AND THE HOLDER ACKNOWLEDGES THAT THE MAY 7, 2002 OPTION WILL BE
SHOWN AS CANCELLED ON THE BOOKS AND RECORDS OF THE COMPANY AND REPLACED WITH
THIS AMENDED AND RESTATED OPTION. THE HOLDER FURTHER AGREES THAT IT WILL RETURN
THE MAY 7, 2002 OPTION TO THE COMPANY MARKED CANCELLED.

         The Company has caused this Amended and Restated Option Agreement to be
executed in the name of the Company by its corporate officer having been duly
authorized, and the Holder has hereunto set Holder's hand and seal as of the
date and year first above written.

INVISA, INC.                              AGREED TO AND ACCEPTED BY HOLDER:
a Nevada corporation                      G.M. CAPITAL PARTNERS, LTD.

By: /s/ Stephen A. Michael, President     By:         /s/ J. A. Michie
   ----------------------------------        -----------------------------------
Its: President                            Its:       Managing Director<PAGE>
                                                                   EXHIBIT 10.51

                                  INVISA INC.
                              2002 INCENTIVE PLAN
                      NONQUALIFIED STOCK OPTION AGREEMENT

Option Agreement Number:                     N-003
Date of Grant/Award:                         June 13, 2002
Name of Optionee:                            Gregory J. Newell
Optionee's Social Security Number:           ###-##-####
Initial Vesting Date:                        September 30, 2002
Initial Exercise Date:                       September 30, 2002
Expiration Date:                             June 12, 2009 (the "Option Term")

         1.       Dated as of the above-stated Date of Grant/Award (the "Grant
Date") a Stock Option (the "Option") is hereby granted to the above-named
Optionee pursuant to the SmartGate Inc. (n/k/a Invisa, Inc.) 2002 Incentive
Plan (the "Plan"). The Award of this Option conveys to the Participant the
right to purchase from Invisa, Inc. (the "Company") up to One Hundred Thousand
(100,000) shares of Stock (the "Option Shares") under the Plan at an exercise
price of $5.10 per share. The Option awarded hereunder is intended to be a
nonqualified stock option subject upon its exercise to treatment, for tax
purposes, under Section 83 of the Internal Revenue Code, and is specifically
not intended to be treated as an Incentive Stock Option, as such term is
defined under Section 422 of the Internal Revenue Code.

         2.       Except as specifically provided herein, the rights of the
Optionee, or of any other person entitled to exercise the Option, are governed
by the terms and provisions of the Plan. The Option is granted pursuant to the
terms of the Plan, which is incorporated herein by reference, and the Option
shall in all respects be interpreted in accordance with the Plan. The Company
shall interpret and construe the Plan and this Option Agreement with respect to
any issue arising thereunder or hereunder, and such interpretations and
determinations by the Company shall be conclusive and will bind the parties
hereto and any other person claiming an interest hereunder.

         3.       To the extent not previously exercised, the Option and all
rights with respect thereto, shall terminate and become null and void when the
Option Term expires.

         4.       Following any termination of Service with respect to the
Optionee, the Option shall be exercisable only during the following timeframes:

                  (a)      DISABILITY. If the Optionee's Service terminates
because of the Optionee becomes disabled, the Option, to the extent unexercised
and exercisable on the date on which Service thus terminated, may be exercised
at any time during the twelve (12) month period immediately following the date
on which the Optionee's Service thus terminated, but in no event any later than
the date the Option Term expires.
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                  (b)      DEATH. If Service terminates because the Optionee
dies, the Option, to the extent unexercised and exercisable on the date on
which the Optionee's Service thus terminated, may be exercised at any time
during the twelve (12) month period immediately following the date on which the
Optionee's Service thus terminated, but in no event any later than the date the
Option Term expires. The Optionee's Service shall be deemed to have terminated
on account of the Optionee's death if the Optionee dies within three (3) months
of the Optionee's termination of Service for any other reason.

                  (c)      TERMINATION TO RETURN TO FULL TIME GOVERNMENT
SERVICE. If the Optionee's Service terminates after June 13, 2005 for the
primary purpose of returning to full-time government service, this Option may
be exercised at anytime following such termination up to the date the Option
Term expires.

                  (d)      OTHER TERMINATION OF SERVICE. If the Optionee's
Service terminates for reasons other than those specifically enumerated, to the
extent the Option remains unexercised and exercisable by the Optionee on the
date on which the Optionee's Service thus terminated, the Option may be
exercised at any time during the three (3) month period immediately following
the date on which the Optionee's Service thus terminated, but in no event any
later than the date the Option Term expires.

         5.       Following the Initial Exercise Date, but subject to such
further limitations provided for herein as may apply, the Option shall become
exercisable as to all or any part of the Option Shares ("Vested Shares")
awarded in accordance with the following Vested Ratio schedule:

<TABLE>
<CAPTION>
            Number of Shares of Stock                  Vesting Date
            -------------------------               ------------------
            <S>                                     <C>
                       5,000                        September 30, 2002
                      10,000                         December 31, 2002
                      15,000                           March 31, 2003
                      20,000                           June 30, 2003
                      25,000                         September 30,2003
                      30,000                         December 31, 2003
                      35,000                           March 31, 2004
                      40,000                           June 30, 2004
                      45,000                         September 30, 2004
                      50,000                         December 31, 2004
                      55,000                          March 31, 2005
                      60,000                          June 30, 2005
                      65,000                        September 30, 2005
                      70,000                        December 31, 2005
                      75,000                         March 31, 2006
                      80,000                          June 30, 2006
                      85,000                        September 30, 2006
                      90,000                         December 31, 2006
                      95,000                          March 31, 2007
                     100,000                          June 30, 2007
</TABLE>

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         There shall be no proportionate or partial vesting in the periods prior
to each Vesting Date, and all vesting shall occur only on the appropriate
Vesting Date, except that in the event of a Change in Control, this Option shall
be deemed fully vested. In the event of Optionee's termination under 4(c) above,
this Option shall be unaffected by such termination and shall remain in full
force and effect for the remainder of the Option Term, vesting in accordance
with the aforedescribed schedule above as Optionee's Services to the Company
shall be deemed to continue in a different capacity as directed from time to
time by the Company's Board of Directors following such termination.

         6.       The Option may be exercised with respect to all or any part
of the number of Vested Shares by the giving of written notice ("Notice") of
the Optionee's intent to exercise to the Company at least five days prior to
the date on which exercise is to occur. The Notice shall specify the exercise
date and the number of Option Shares as to which the Option is to be
exercised. Full payment of the Option exercise price by any of the means of
consideration provided for under the Plan shall be made on or before the
exercise date specified in the Notice. Such full payment having occurred on or
before the exercise date specified in the Notice, or as soon thereafter as is
practicable, the Company shall cause to be delivered to the Optionee a
certificate or certificates for the Option Shares then being purchased. If the
Optionee fails to pay for any of the Option Shares specified in the Notice, or
fails to accept delivery of Option Shares, the Optionee's right to purchase
such Option Shares may be terminated by the Company.

         7.       During the Optionee's lifetime, the Option granted hereunder
shall be exercisable only by the Optionee or by any guardian or legal
representative of the Optionee, and the Option shall not be transferable
except, in the case of the death of the Optionee, by will or by the laws of
descent and distribution, nor shall the Option be subject to attachment,
execution or other similar process.

         8.       The Company may unilaterally amend the Option Award at any
time if the Company determines, in its sole discretion, that amendment is
necessary or advisable in light of any applicable addition to or change in the
Internal Revenue Code, any regulations issued thereunder, or any federal or
state securities law or other applicable law or regulation.

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         9.       Until the date a Stock certificate is issued to an Optionee,
an Optionee shall have no rights as a stockholder with respect to the shares of
Stock subject to Award under this ISO Agreement, and no adjustments shall be
made for dividends of any kind or nature, distributions, or other rights for
which the record date is prior to the date such Stock certificate is issued.

         10.      The Optionee acknowledges having received and read a copy of
the Plan and this Agreement and agrees to comply with all laws, rules and
regulations applicable to the Award and to the sale or other disposition of the
Stock of the Company received.

         11.      In the event the Optionee should cease to be employed by or
to provide Services to the Company, the Company hereby reserves a right to
repurchase from Optionee, at its sole discretion, any or all shares issued to
Optionee under the Plan which have been outstanding in excess of six months.
Company is to pay to Optionee under such repurchase the Fair Market Value of
the shares on the date of such repurchase and Optionee will, from that point
onward, have no further shareholder rights with respect to those shares. The
Company hereby reserves a right of first refusal on all the awarded shares
which have been outstanding in excess of six months. During this time, prior to
selling any shares, the Optionee must notify the Company, in writing, of the
terms of the transaction in which the Optionee proposes to sell the shares.
Such notice shall be supported by a bona fide formal letter of arrangement.

         The bona fide formal letter of arrangement must include (i) all of the
terms of the transaction, (ii) a description of any financing arrangements
related to the transaction, and (iii) full disclosure of all parties, whether
agent or principal, who are interested in the transaction.

         The Company shall have sixty (60) days to determine if it or other
stockholders in the Company will purchase the shares. The Company shall respond
by the sixtieth (60th) day after receipt of the Optionee's notice or forfeit
its rights under this paragraph. If the Company decides that neither it nor any
other stockholders in the Company shall purchase the shares, the Optionee must
engage in the transaction as described in the notice provided to the Company
within sixty (60) days; otherwise, the Company's first refusal right shall
again be applicable to any subsequently proposed sale of the shares.

         12.      Any notice to the Company provided for in this Agreement
shall be addressed to it in care of its Secretary at its executive offices
located at 4400 Independence Court, Sarasota, Florida 34234, and any notice to
the Optionee shall be addressed to the Optionee at the address currently shown
on the payroll records of the Company. Any notice shall be deemed duly given if
and when properly addressed and posted by registered or certified mail, postage
prepaid.

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         IN WITNESS WHEREOF, Invisa, Inc. has caused its duly authorized
officers to execute this nonqualified Stock Option Agreement, and the Optionee
has placed his or her signature hereon, effective as of the Grant Date.

INVISA, INC.

Attest:

By: /s/ Stephen A. Michael
   ------------------------------------
Title: President

ACCEPTED AND AGREED TO:

By: /s/ Gregory J. Newell
   ------------------------------------
   Gregory J. Newell, Optionee

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